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.
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 ("-").
Error Checks Mode: added linedef index to message text of all linedef-related errors.
UDMF: wall texture offsets are now rounded when user edits them via cursor keys or mouse dragging (because they are stored as integers anyway).
