Optimized map geometry merging performance when pasting map geometry.
Added, Curve Linedefs mode: added "Flip Curve" button.
Updater: partially rewrote fix from the previous commit.

Changed, Curve Linedefs mode: re-designed the mode UI. Alternative control options are now available (check Help tab while the mode is active).
Changed, Curve Linedefs mode: changed curve generation logic. Setting Distance to 0 will now divide selected linedefs into equal parts.
Changed, Curve Linedefs mode: curve vertices are now drawn.
Updated ZDoom_DECORATE.cfg.

Added, Game configurations: added "ignoreddirectories" parameter. It lists directory names to be ignored when loading PK3/PK7/Directory resources.
Added, Game configurations: added "ignoredextensions" parameter. It lists file extensions to be ignored when loading PK3/PK7/Directory resources.
Updated: sector triangulation logic now works ~20% faster.
Changed: a case when a pk3/pk7 archive contains several entries with identical filename is now treated as a warning, not as an error.
Fixed, Visual mode: absolute floor/ceiling brightness should not be affected by brightness transfer effects (like 3d floors).
Fixed, Draw Lines mode: in some cases unclosed sectors were created when several points were successively drawn at the same location.
Updated documentation. 

Updater: moved SharpCompress code into a separate embedded library. Seems to stop some anti-viruses detecting it as a trojan/virus.
Updated ZDoom_DECORATE.cfg (A_SetInventory).

Updated ZDoom_DECORATE.cfg.
Updated documentation ("Game Configuration - Sectors Settings" page).

Added: some numeric text inputs now support expressions (e.g. (23+15)*1.5). - inspired by https://www.doomworld.com/vb/doom-editing/91089-gzdoombuilder-patch-expression-evaluation-for-sector-heights/
Fixed, Game Configurations window: fixed a crash when switching to a game engine without the file path using the "Engine" drop-down.

Changed the way editor is closed during the update process (updater now asks to close the editor after downloading the update package).
Added write access check before performing the update.
The editor can now update the updater.
Updater: merged relevant parts of SharpCompress into the updater source, reducing updater file size from 900 kb to 150 kb.
Updated ZDoom_DECORATE.cfg.

Updater: error messages now display more info.
Updater: editor closing step is now performed after downloading the update.
Updater: added taskbar progress indication.
NOTICE: to obtain the updated updater, you'll need to download GZDB manually from http://devbuilds.drdteam.org/doombuilder2-gzdb/, because the updater can't update itself.
Added Updater source.

Added, Things mode: sound radii are now shown for "Custom Ambient Sound" and "Custom Ambient Sound (no gravity)" things.

Updated, Visual mode: unflipped FLATSPRITEs.
Updated, DECORATE parser: added duplicate actor definition check.

Fixed, Visual mode: things in sectors affected by line slope effect were not updated when sector height was indirectly changed.
Game configurations: added "internalsoundnames" property.
Updated documentation ("Game Configuration - Basic Settings" page).

Added, Things mode: minimum/maximum sound radii can now be displayed for ZDoom's Ambient Sound things.
Added, Things mode: added "Show Light Radii" and "Show Sound Radii" main toolbar and View menu buttons.
Fixed, Action arguments control: invisible splitter between args1-3 and args4-5 is no longer draggable.
Updated ZDoom ACC (SetTranslation).
Updated ZDoom_ACS.cfg (SetTranslation).

Changed, Vertices/Linedefs/Sectors/Things modes: selected map element is no longer deselected after accepting Edit window when it was the only selected map element when the Edit window was opening.

Added: guidelines can now be enabled in Draw Rectangle/Ellipse/Grid modes.
Changed, Draw Lines mode: perpendicular guidelines are now drawn for horizontal/vertical lines.
Updated, Draw Ellipse mode: the shape now always touches all sides of the bounding box.
Updated ZDoom_ACS.cfg.
Updated ZDoom_DECORATE.cfg.
Updated ZDoom ACC.

Changed, Visplane Explorer mode: calculated data is now fully reset when toggling "Open doors" option.
Changed, Visplane Explorer mode: vpo.dll is now initialized when entering the mode instead of after opening a map.
Fixed inconsistent Hexen Puzzle Gears names between game configuration and spawn numbers list.
Updated ZDoom_DECORATE.cfg (GetMissileDamage). 

Fixed, Things mode: thing selection labels must be updated when performing undo/redo.
Fixed another case of invalid sectors being created after dragging map elements when using "Merge Dragged Geometry" and "Replace with Dragged Geometry" drag modes.

Added, Map Analysis mode: added "Edit Thing..." option to "Unknown Thing" and "Obsolete Thing" error check results.
Added: a warning is now displayed when a thing has both voxel and model attached.
Changed, Thing/Linedef Info panels: unknown ACS script names/numbers are now shown in red.
Fixed, Edit Things window, UDMF: unneeded undo was created when opening the window.
Re-fixed: in some cases invalid sectors were created after dragging map elements when using "Merge Dragged Geometry" and "Replace with Dragged Geometry" drag modes, when at least one of dragged linedef was facing into an enclosed void area (previous fix entirely disabled the associated logic).

Updated ZDoom ACC (SetActorFlag).
Updated ZDoom_ACS.cfg (SetActorFlag).

Fixed: in some cases lines with only back side were created after dragging map elements when using "Merge Dragger Vertices Only" drag mode.
Fixed: in some cases invalid sectors were created after dragging map elements when using "Merge Dragged Geometry" and "Replace with Dragged Geometry" drag modes, when at least one of dragged linedef was facing into an enclosed void area.
Fixed a crash after drawing lines over a sector with unclosed/invalid boundaries.
Fixed(?): probably fixed a crash when closing Script Editor with an unsaved file during program termination.

Fixed: stored windows positions were not checked against current screen bounds, which may have resulted in windows being shown off-screen.

Fixed, Visual mode, UDMF: only the clicked floor/ceiling surface was dynamically updated when changing texture offsets of multiple floors/ceilings by mouse-dragging.

Merged "Toggle models, dynamic lights and fog rendering" and "Toggle Geometry Effects" actions into "Toggle Enhanced Rendering Effects" action.
Removed "Dynamic light size" and "Dynamic light intensity" settings.
Updated documentation ("Rendering toolbar" page).

Fixed, Visual mode: in some cases mouse cursor movement was not clipped to the render area when focusing the editor after Alt-Tabbing from the Visual mode.
Addressed, Line drawing: in some cases extra vertices were created when drawing lines on top of nearly parallel non-cardinal lines.

Updated, Visual mode, UDMF: "Change Texture Scale" actions now take camera and texture angles into account when used on floors/ceilings.
Changed: "+++" and "---" prefixes are now incremented on the first step instead of the second when used in any numeric inputs, which support prefixes, except action arguments.
Fixed, Visual mode, UDMF: texture offset/scale/rotation changes were applied several times when used on several 3d-floor floors/ceilings linked to the same control sector, when using "Move Texture Offsets" / "Change Texture Scale" / "Rotate Texture CW/CCW" actions.
Updated ZDoom ACC (DamageActor).
Updated ZDoom_ACS.cfg (DamageActor).

Added "localsidedeftextureoffsets" Game configuration setting. When set to true, enables in-editor support for individual offsets of upper/middle/lower sidedef textures. Affects UDMF map format only. - based on diff patch by Altazimuth.

Fixed several cases when certain texture manipulation-related actions caused a crash when performed on not-yet-loaded textures.

Fixed, text parser: fixed a case when the parser tried to rewind before beginning of the stream when parsing unknown #block, when it was the first token of the file.

Fixed, updater: fixed "Unable to locate updater.ini" error when the editor was launched using "Open with..." shell command.