Visual mode: added support for "Transfer Floor Brightness" (210) effect.
Visual mode: added support for "Transfer Ceiling Brightness" (211) effect.
Visual mode: changed the way thing brightness is calculated. Should be closer to GZDoom now.
Sector Edit Form: you can now enter "++" or "--" into "Height Offset" input to raise or lower sectors by their height.
Cosmetic fix in ZDoom_linedefs.cfg.