Fixed several bugs in Engine selector dialog ("Game configurations -> Testing").

Linedef edit form: action arguments were set to zero when settings were applied to several lines with different argument values (instead of being kept unchanged).

Linedef edit form: all linedef UDMF properties are now editable via user interface + some fixes in sidedef UDMF controls. 

Fixed a typo in one of Visplane Explorer messages.
Small fixes here and there.

Increased screenshot jpeg quality to 90.

"Clear Group" 2-10 actions had incorrect default shortcuts.

Added some boilerplate to SaveScreenshot function.

Default flag ("playercross") was not set when a map was converted to UDMF map format (because there are no default flags in UDMF).
Linedef activation now translates a bit more accurately when converting a map to/from UDMF.

Screenshots of GZDB window and edit area can now be saved (Tools -> Save Screenshot and Tools -> Save Screenshot (edit area)).
NumericTextbox now uses NumberDecimalSeparator instead of CurrencyDecimalSeparator.

Map Analysis mode: only a single undo is now created when multiple similar errors are fixed using "Apply to all errors of this type" checkbox, which greatly reduces errors fixing time.

Vertex edit form: it was impossible to enter fractional position and zOffset values even if map format supported it. 

"thingflagstranslation" block was missing from UDMF game configuration, so thing flags were dropped when map format was changed to UDMF.

Removed some unused "using" directives.

Linedefs mode: added "Align Floor Texture to Front Side", "Align Floor Texture to Back Side", "Align Ceiling Texture to Front Side" and "Align Ceiling Texture to Back Side" actions (available in Linedefs -> Align Textures menu).

Visual mode, UDMF: "Auto-align textures" actions now work for floors and ceilings. Textures are aligned to a linedef of highlighted floor/ceiling, which is closest to 3d-cursor position.

Added "SetCVarString", "SetUserCVarString", "GetCVarString" and "GetUserCVarString" functions to ACS configuration.

Linedef colors were not updated properly when a map format was changed and were causing an exception in some cases.
Vertices mode: linedef in split linedefs range was redreawn incorrectly in some cases.
Updated "Sector 3D Floor" (160) action: set default Type to Solid (1), added "Use Arg5 as Line ID" flag to Types, changed arg5 name to "Line ID / Hi-Tag".
Added "GetUserCVar", "SetCVar" and "SetUserCVar" functions to ACS configuration.
Set width and height of several actors to 0 in game configutrations (non-zero sizes were added as a workaround when GZDB was not displaying actors with 0 width and height in Visual mode).
Added several sprites to game configurations.

Classic Modes: added 3D floor indication (color can be changed in Preferences -> Appearance -> 3D Floors).
Sector_Set3dFloor action (160): added hi-tag/line ID check.

Visual Mode, UDMF, Visual Vertices: heights of vertices without z-offset was incorrect in some cases.
Visual Mode, UDMF, Visual Vertices: vertices without z-offset are now rendered using Vertex color (Preferences -> Appearance -> Vertices).

Visual Mode, UDMF: added "Fit Texture", "Fit Texture's Width" and "Fit Texture's Height" Actions.cfg
Visual Mode, UDMF, Visual Vertices: you can now press "Delete" key to clear z-offsets of selected vertices.
Visual Mode, UDMF, Visual Vertices: the logic, which decides whether z-offset should be kept or removed, was not working properly.
Visual Mode, UDMF: Auto-align Textures (Y) action was not working properly when targeted texture was lower wall without "Lower Unpegged" flag.

Visual Mode, UDMF: "Auto Align Textures" actions now work on slopes.
Visual Mode, UDMF: Floor/ceiling texture rotation is now taken into account when moving texture offsets with arrow keys.
Visual Mode, UDMF: Fixed a bug in floor/ceiling texture dragging by mouse.

DECORATE: When an actor inherits from an actor, defined in Game configuration, values from Game configuration are used if an actor doesn't define them.
UDMF Controls plugin: changes made using plugin were not properly undoable.

UDMF: Reset texture offsets action now works on floors and ceilings.
Vertices mode: when a linedef is within Split Linedefs range, it's now highlighted using Info line color.

Some cosmetic changes in Bit flags form.

Fixed: Incorrect articles were sometimes used in Draw Geometry/Curve/Rectangle/Ellipse info messages. 

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.

Rectangular Selection: removed direction-based additive/subtractive selection. You can now hold Ctrl to enable subtractive selection, hold Ctrl-Shift to intersect with existing selection.
Point Thing at Cursor action: action now works when used from menu, changed default shortcut to Shift-L. You can now hold Ctrl to point Things away from cursor.