Updated documentation.

ZDoom_linedefs.cfg: "Plane" actions don't require activation.

Visual mode, "Raise Floor/Ceiling to adjacent sector", "Lower Floor/Ceiling to adjacent sector": things with "absolutez" flag should be handled differently. 

Fixed, Visual mode: in some cases "Raise Floor/Ceiling to adjacent sector" was not working properly when used on things.

Fixed, Visual mode: a case when thing's height was bigger than distance between floor and ceiling's planes is now handled the same way as in ZDoom.

Fixed, Visual mode: when thing's position is not absolute, it should always be positioned between floor and ceiling planes.

Sound Environment mode: you can now add sound environment things using "Insert Thing" or "Edit Selection" actions (just like you add things in Things mode).
Sound Environment mode: you can now delete currently highlighted sound environment thing by using "Delete" action.
Sound Environment mode: the sidebar panel icons now have the same colors as corresponding sound environments.
Fixed, Sound Environment mode: in some cases several sidebar panel items were highlighted at once (I broke this in r2201).
Fixed, Fit Textures action: lower linedef parts were aligned incorrectly.
Changed, Fit Textures Options form: "Fit across multiple surfaces" checkbox is now disabled when the action is applied to a single surface.

Fixed, Sectors Mode, UDMF: "Make Brightness Gradient" action was not working when "Sector Brightness" mode was selected... 

Visual mode, UDMF: renamed "Scale Texture Up/Down (X/Y)" actions to "Increase/Decrease Horizontal/Vertical Scale". These actions can now be used on things.

Fixed, DECORATE parser: "scale", "xscale" and "yscale" properties are now parsed the same way as in ZDoom.
Fixed, DECORATE parser: parser was unable to parse negative numeric properties.

Fixed, Texture previews: texture size labels were displaying incorrect size or no size at all when showing TEXTURES textures with negative scale.
Fixed, Visual mode, UDMF: when several wall parts were selected, only one could be dragged with the mouse.
Fixed, Visual mode, Auto-align textures, UDMF: TEXTURES scale is now taken into account when aligning textures.
Fixed, Visual mode, Auto-align textures (Y), UDMF: nearest height matching is now applied to non-wrapped middle backsides.
Cosmetic changes in ZDoom_ACS.cfg.

Linedef/Thing Edit forms: cosmetic changes to named/numbered script drop-down locations.

Changed, Edit Sector/Linedef/Thing/Vertex forms: undo is now created either when user changes a value using a real-time control or when applying changes, not when opening a form.

Updated ZDoom_DECORATE.cfg.

Changed, Sound Environment mode: on second thought, we don't need to scan all map things to find one to highlight...

Sound Environment Mode: sound environments can now be picked by editing sound environment things.
Sound Environment Mode: detected sound environments names are now used as item names in the tree view.
Fixed, Classic modes: incorrect texture was used as unknown floor/ceiling texture (I broke this in r2199).
Fixed, MainForm: reverted MainForm.UpdateToolStripSeparators. By making it look simpler I made it work more buggy...
Updated ZDoom_DECORATE.cfg.

Fixed: flats and textures defined in TEXTURES should override regular ones (adding long texture names support broke this).
Removed unused references from all projects.

Changes since 5bf51d0:
Large scale cleanup & refactoring.
Sound Propagation Mode: you can now click on doublesided linedefs to toggle sound blocking flag.
Sound Environment Mode: you can now click on doublesided linedefs to toggle sound zone boundary flag.
Sound Propagation Mode: reimplemented the highlighting of non-deaf things. Things are now highlighted using selection color.
Removed "Show tooltips" checkbox. Tooltips are now always enabled.
Fixed, Sound Environment Mode: thing tooltip about multiple active sound environment things was shown even when there was only one active sound environment thing.
Fixed, Sound Environment Mode: "Configure colors" toolbar button was not working because of missing action.
Fixed, cosmetic: "Configure colors" toolbar icon was missing a tooltip.
Fixed, cosmetic: display was not redrawn after changing colors using "Color configuration" window.

Fixed, Thing Browser Control: "Multiple Things" icon was assigned to BackgroundImage instead if Image.
Updated ZDoom_DECORATE.cfg.

Fixed, Script Editor: named scripts were not shown in the script navigator drop-down when current map was not in UDMF.

Changed, Script Editor: changed text cursor behavior when selecting an item in the script navigator drop-down to Visual Studio-like.

Moved stuff around a bit in PK3Reader. Will it fix random crashes? I dunno, a least I was no longer able to trigger them...
Recompiled SharpCompress library using VS 2008, so it no longer references .net 4.0 stuff. Will it fix random crashes? See above.

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. 

Script Editor: fixed an exception when a script configuration contained identical keyword and constant.
ZDoom_DECORATE.cfg: added a bunch of actor properties.

PK3Reader: probably fixed a random sharpcompress crash when trying to access a closed file (totally unsure, need more testing).
ZDoom_linedefs.cfg: fixed a typo.

ZDoom_misc.cfg: added an empty "spawn_projectile" enumeration to prevent warnings when game-specific enums group doesn't contain this enum.
Game_Chex.cfg was misplaced.

Fixed, Sectors mode, UDMF: surface cache was not updated after applying floor/ceiling brightness gradients.
Cosmetic, Sectors mode, UDMF: brightness gradient modes now have more descriptive names.
Internal, InterpolationTools: replaced EaseInOutSine equation with one, which actually works.

Sectors mode: "Gradient Interpolation Mode" toolbar menu.
Internal: extracted easing functions from Bridge Mode into InterpolationTools class.
+a couple of cosmetic changes.

Fixed: texture coordinates interpolation during linedef splitting was failing in UDMF map format when target sidedef's texture was in a sub-folder of a PK3 or Folder resource.

Visual mode, "Raise/Lower Sector to Nearest" actions: both floor and ceiling heights of adjacent sectors are now taken into account.

Fixed (DB2 bug): the first texture of every TEXTURE1 lump should be ignored, not the first texture loaded from the first map resource. Also, said texture(s) are no longer shown in the Textures browser.
Cosmetic update in ZDoom_DECORATE.cfg.

+a couple of cosmetic changes.

Fixed, Fit Textures action: sidedefs were not sorted properly when trying to use the action on several disconnected sidedef strips with the same texture.
Fixed, Fit Textures action: update was not triggered when toggling "Fit across connected surfaces" check-box.

Map Analysis mode: selection color is now used when rendering affected things.
Fixed, Map Analysis mode, "Check unused things" check: checker returned false-positive results when used in Doom map format.