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 ("-").
When no configuration is enabled, a message was supposed to be shown after startup. Now it actually shows up.
Several configurations were missing from the "Configurations" folder.
Configurations: all 64 game configuration are now available by default.
Game Configurations window: game configurations can now be disabled. This setting is mostly cosmetic. When a game configuration is disabled, it won't be shown in "game configuration" dropdowns in New\Open Map Options and Map Options windows. If a map's .dbs file specifies a disabled configuration, it will be picked as a map configuration anyway.
Linedefs mode: vertex insert preview logic used Highlight range instead of Stitch range (which is used when draw mode engages).
Visual mode: double-sided middle textures were not selected when using "Select" action with "with same texture" modifier.
Textures: some optimizations in patch blending code.
ZDoom ACS script configuration: added definitions for StrLeft, StrMid and StrRight functions.
Floor and ceiling textures are now moved more predictably by arrow keys in GZDoom Visual mode.
Walls texture coordinates are always rounded when moved by arrow keys in Visual modes.
Linedef info panel: relative UDMF light values are now shown like this: 16 (128), which means "UDMF light value" ("total surface brightness (UDMF light value + sector brightness)")
Player is now spawned at camera height when testing from current location in Visual modes.
Focus is now properly restored after testing from current location in Visual modes.
Updated Heretic_sectors.cfg and Heretic_things.cfg as described here: http://www.doombuilder.com/forums/viewtopic.php?f=11&t=357
Changed sprites of artifacts in Hexen_things.cfg to proper ones.
Renamed Skulltag configs to Zandronum
