Fixed, Texture Browser Form: well, I broke "Tab" key functionality again (in previous commit)...
Maintenance: changed curly braces style to match DB2 one (hopefully not breaking anything in the process...).
Maintenance: changed private method names casing to match DB2 one.
Thing Edit Form, UDMF: added controls for setting pitch, roll, scale, render style, fill color, alpha, health and score.
Visual mode, UDMF: UDMF scale is now applied when rendering sprites.
Added Thing Statistics form (Edit -> View Thing Types...), which shows all loaded thing types with some additional info.
Visual mode: sprites with negative ScaleX and positive ScaleY were not rendered properly.
Classic modes: display was not updated after loading a sprite.
Current testing engine change was not saved on closing the program when no other game configuration settings were changed.
Error checks: added "Check unused textures" option.
Replaced MissingTexture3D and UnknownTexture3D.
Sectors mode: restored "Lower/Raise Floor/Ceiling by 8 mp" actions.
Visual mode: in some cases sidedefs were rendered as selected when they were not.
Existing linedefs were not split while drawing new lines in some cases.
Texture and height overrides were not applied correctly in some cases.
Preferences form: "Ctrl+Alt+ScrollUp" and "Ctrl+Alt+ScrollDown" dropdown items were setting the shortcut to "Ctrl+Shift+ScrollUp" and "Ctrl+Shift+ScrollDown".
