- reorganization of automap color handling for easier maintenance

Mostly preparation to implement a per-mod automap option but also fixes a few minor issues with some colors that are not defined in the original game specific colorsets.
- ovthingcolors were not properly set.
- added all the missing color CVARs for the overlays which previously duplicated use of one of the other CVARs.
- implemented automap color parser for MAPINFO (code not tested yet!)
- fixed typo in MENUDEFS.
Merge branch 'automap_colors'