Sectors Mode: fixed a problem where dragging a single highlighted sector did not move the things in the sector when synchronized things editing was enabled

Drag Geometry Mode: floor and ceiling panning are now correctly preserved when dragging geometry. Fixes 648

Added option to lock texture offsets of 3D floors when dragging the tagged sectors

Added, Find & Replace mode, UDMF: added Linedef activation flags to the "Find Linedef flags" search mode flags list.
Changed, Sound Propagation mode: all sound zones are now shown when no sector is highlighted.
Changed, Sound Environments mode: the mode is now available only in UDMF map format.
Changed, Color Picker plugin: the plugin functionality is no longer available in Doom map format.
Restored the ability to create superimposed lines by dragging them with "Snap to Geometry" mode disabled.
Fixed, Sound Propagation mode: fixed a crash when a single-sided linedef had "Block Sound" flag.
Fixed, Find & Replace mode: in some cases "Find Sector/Sidedef/Linedef/Thing flags" search modes failed to find map elements with required flags.
Fixed, Edit Selection mode: in some cases incorrect geometry was created after applying multipart sector edit when "Replace with Dragged Geometry" mode was enabled.
Fixed a crash caused by eventual GDI font objects overflow.

Added 3 map geometry dragging modes (used when applying Drag Vertices/Linedefs/Sectors modes and Edit Selection mode):
- "Merge Dragged Vertices Only". Only vertex-line intersections will be processed (DB2 mode).
- "Merge Dragged Geometry". Geometry merging will be performed.
- "Replace with Dragged Geometry". Dragged geometry will replace underlaying geometry.
You can switch between these using 3 new actions, top toolbar buttons and Edit menu buttons.
Changed: activating the same 2D mode repeatedly now toggles View modes.
Renamed "Merge Geometry" action/menu item to "Snap to Geometry".
More fixes to vertex/linedef/sector dragging logic.
Updated ZDoom_DECORATE.cfg.

Rewritten vertex/linedef/sector dragging logic. Now it processes line-line intersections. And handles more corner cases. And has less bugs. Probably.
Fixed, Edit Selection mode: texture scale was flipped when "Floor/Ceiling Transform" -> "Scale" was enabled.
Changed: a warning is no longer displayed when trying to compile an empty SCRIPTS lump.
Updated ZDoom_DECORATE.cfg.

Added: sectors are now split into multiple sectors when their shape is divided into several closed shapes by drawing new geometry or dragging existing geometry using Edit Selection and Drag Geometry modes.
Fixed: in some cases sidedefs belonging to linedefs, which were moved on top of existing linedefs, were incorrectly reassigned when applying Edit Selection and Drag Geometry modes.
Fixed: Tag Explorer update fix from R2630 was accidentally placed in an UDMF-only if-block.
Updated ZDoom_DECORATE.cfg (A_WeaponOffset).
Updated documentation ("(G)ZDoom text lumps support" page).

Fixed, Tag Explorer: in some cases (for example, when geometry was removed implicitly by dragging geometry) the list was not updated.
Fixed: in some cases generalized sector effect detection logic failed to detect a valid generalized effect.
Fixed, Action selector control: action label was not updated when changing action number from one generalized effect to another.

Fixed, Map Analysis mode, "Check stuck things" check: rewritten parts of the flags checking logic to allow more accurate flag checks.
Fixed, Map Analysis mode: fixed a crash when trying to dissolve an invalid sector when one of it's linedefs referenced it on the both sides.
Fixed, Sectors mode: fixed incorrect undo description when deleting sectors.
Internal: joined declaration and assignment of some more variables.

Internal: joined declaration and assignment of some variables.

Sectors mode: removed "Move Things in Selected Sectors" toolbar button.
Sectors mode: added "Synchronized Things Editing" menu item, action and toolbar button. When enabled, things dragging will be synchronized to sector dragging. Regular, Paint and Rectangular selection will also select things (holding Alt while selecting inverts this behavior). Deleting sectors will also delete selected things.
Linedefs mode: added "Synchronized Things Editing" menu item, action and toolbar button. When enabled, selected things will be dragged when dragging linedefs. Rectangular selection will also select things (holding Alt while selecting inverts this behavior).
Changed: selection info now always displays info about all types of map elements.
Fixed: .dbs containing only current map settings was created when trying to save unchanged map. 
Fixed, Visual mode, "Copy Texture" action: when "Use long texture names" option is disabled, texture name as stored in Sidedef should be used, not the 8-char texture name.
Updated documentation.

Added emergency map backup system (EMBS). When the editor crashes, it will try to export a backup copy of the map structures. When the same map is loaded again, it will ask the user if he wants to restore the map.
High-DPI: fixed many issues with incorrect controls size (Tag selector width, Comment Editor size, icons size, tabs size etc.).
Cosmetic: changed map geometry dragging undo messages to more descriptive ones.
Fixed, Textures Browser, cosmetic: "Show textures in subdirectories" checkbox should be repositioned when "Long texture names" one is invisible.
Updated ZDoom_DECORATE.cfg (added A_SetFloatSpeed + a couple of fixes).

Changed, Visual mode: changed thing fog calculation logic. Should be closer to GZDoom now.
Fixed, GLDEFS parser: "height" texture parameter was not treated as optional.
Fixed, text lump parsers: in some cases incorrect line number was displayed in error and warning messages.
Fixed, Visual mode: glow effect was not applied to sectors with 3 sidedefs.
Fixed, Visual mode: in some cases glow effect was not updated when replacing textures. 
Fixed, general interface: "Full Brightness" button state was not updated during map loading.
Fixed, Drag Linedefs/Vertices/Sectors/Things modes: positions of line length labels were not updated while panning the view.
Cosmetic: added a bunch of new icons.
Cosmetic: changed Visual mode crosshair.

Changed, Drag Linedefs/Vertices/Sectors/Things modes: line length labels are now displayed the same way as in Draw modes.
Changed, Drag Linedefs/Vertices/Sectors/Things modes: "lock movement to cardinal directions" mode (Alt-Shift-Drag) now locks movement in 4 directions instead of 8 and doesn't snap map elements to nearest grid intersections when they are not aligned to it. 
Added, Visual mode, GZDoom, DECORATE: FORCEXYBILLBOARD flag is now supported.
Added, Visual mode, GLOOME, DECORATE: FLOORSPRITE, CEILSPRITE, WALLSPRITE, ROLLSPRITE and STICKTOPLANE flags are now supported (implementation is somewhat broken ATM and probably doesn't work the same way as in GLOOME, because Windows build with most these features is nowhere to be found...).
Fixed, Visual mode: in some cases Thing brightness was calculated incorrectly.
Updated ZDoom_DECORATE.cfg.

Changed: current 2D position and zoom is now stored in the .dbs file when saving the map and restored when opening it (should this be turned into toggleable option?).
Draw Lines mode, Draw Curve mode: you can now hold Alt - Shift to snap to 8 cardinal directions.
Draw Rectangle mode, Draw Grid mode: you can now hold Alt - Shift to draw square shapes.
Draw Ellipse mode: you can now hold Alt - Shift to draw circle shapes.
You can now hold Alt - Shift to snap to 8 cardinal directions while dragging map objects.
Fixed, Draw Lines mode: line angle is now displayed in 0..359 range (was -45..314).
Fixed, Linedef info panel: line angle is now displayed in 0..359 range (was -45..314).

Edit Selection mode, UDMF: sector slope offsets are now updated to keep them at the same position when moving or rotating sectors.

Drag Geometry mode, UDMF: sector slope offsets are now updated to keep them at the same height when moving sectors.

Visual mode: "Auto-align textures" actions now align mixed textures when used on a selection (helpful if you want to align several different textures, which can tile into each other).
Cosmetic: errors and warnings are now cleared when reloading resources. 

Fixed, Texture Browser Form: well, I broke "Tab" key functionality again (in previous commit)...
Maintenance: changed curly braces style to match DB2 one (hopefully not breaking anything in the process...).
Maintenance: changed private method names casing to match DB2 one.

Fixed, Classic modes: Alt-dragging map elements (e.g. "snap to grid increment while dragging" mode) was not working properly.

Fixed: Drag Geometry Mode: dragged sectors, linedefs or vertices were snapped to 0, 0 in some cases when trying to snap them to a linedef fully inside of a grid cell.

Sectors mode: things inside of selected sectors can be moved when dragging sectors. This behavior can be toggled by the new button on Sectors mode's toolbar.
Sectors mode: changed Alt-key handling. Now it only enables "snap to grid increment" mode.
Things mode: "snap to grid increment" mode now works in this mode.
Updated documentation.

Classic modes: you can now hold ALT key while dragging map items to lock movement to grid increments relative to initial position.

Linedef Edit Form, Sector Edit Form: when several map elements with different textures are selected, the "texture stack" icon is shown in the texture selectors instead of the "missing texture" icon.
Error Checker mode: added "Check missing flats" check.
Error Checker mode: fixed several descriptions. 
Sprite patches for sprites defined in TEXTURES are now loaded from Sprites namespace.
Some of my older texture alignment code didn't work properly when strict texture/flat handling ("mixtextureflats" game configuration flag set to false) was enabled.
Fixed some incorrect checks for missing texture ("-").

Numeric textbox: in addition to '++NN' and '--NN', you can use '*NN' and '/NN' to multiply or divide the values.
Configurations, ZDoom_linedefs.cfg: some linedef action arguments were missing a proper type.
Rewritten parts of hints system. Hints are now loaded from "Hints.cfg" file.

Error checks: added "Check unused textures" option.
Replaced MissingTexture3D and UnknownTexture3D.
Sectors mode: restored "Lower/Raise Floor/Ceiling by 8 mp" actions.
Visual mode: in some cases sidedefs were rendered as selected when they were not.
Existing linedefs were not split while drawing new lines in some cases.
Texture and height overrides were not applied correctly in some cases.
Preferences form: "Ctrl+Alt+ScrollUp" and "Ctrl+Alt+ScrollDown" dropdown items were setting the shortcut to "Ctrl+Shift+ScrollUp" and "Ctrl+Shift+ScrollDown".

Added hints for Drag Geometry modes.

Visual mode: changed "Move Texture Left/Right/Up/Down by 8" actions to "Move Texture Left/Right/Up/Down by cur. grid size"
Visual mode: holding Ctrl-Shift while dragging texture with the mouse will snap texture offsets to current grid size.
Classic modes: interiors of highlighted sectors are now highlighted when the action target of currently highlighted map element is sector.
Unhandeled exceptions infos are now written to the event log.

Textures now load up to 2x faster when "mix textures and flats" flag is set in game configuration.
TEXTUREx/TEXTURES: texture will now be created if at least one of it's patches is loaded.
Visual mode: fixed a crash when "Slope floor to here" (9500) or "Slope ceiling to here" (9501) things were not inside sector.
Fixed: flats were not loaded form wads inside Directory and PK3/PK7 resources.
Sector Info Panel, Linedef Info Panel: texture size was shown for unknown textures.

Classic modes, UDMF: floor/ceiling texture offsets can now be locked in place while sector is dragged.
Fixed another bug in Tools.autoAlignTexturesOnSidesUDMF()
Replaced Math.PI-related equations with stuff from Angle2D class.

- Fixed a problem in the linedef info panel where the linedef numbers was displayed instead of the sidedef number
- Fixed a problem where dragging geometry and things onto the window title bar locked up DB2
- Fixed a problem with wrong texture offsets of hi-res textures

- Progressive undo/redo system (much faster and up to 1000 undo/redo levels) Please note that several plugin functions and properties have changed.
- Some small optimizations in the classic 2D rendering (cached linedef flags, reduced some unneeded redrawing)