Sound Environment Mode: sound environments can now be picked by editing sound environment things.
Sound Environment Mode: detected sound environments names are now used as item names in the tree view.
Fixed, Classic modes: incorrect texture was used as unknown floor/ceiling texture (I broke this in r2199).
Fixed, MainForm: reverted MainForm.UpdateToolStripSeparators. By making it look simpler I made it work more buggy...
Updated ZDoom_DECORATE.cfg.
