GRAPHICS: Serialize PixelFormat for thumbnails and allow 4Bpp surfaces.

This allows any 2Bpp/4Bpp Surfaces to be written via saveThumbnail
and loadThumbnail now. It furthermore will preserve the loaded Surface
in loadThumbnail.
SCI32: Add some notes about KScrollWindow/Add
SCI32: Add notes about KScrollWindow/Where,Go
SCI32: Add more KScrollWindow notes
SCI32: Add more KScrollWindow notes
GROOVIE: Simplify the movie speed settings and add a GUI option

This removes the "iOS" speed setting, where some movies could get out
of sync. Two movie options are now available, "normal" and "fast" movie
speed, which is the old "tweaked" setting. With the "fast" movie speed,
the movie speed is changed to match that of the iOS version, but only
in movies with sound. Movies without sound (like the supernatural
animations, i.e. the "teeth" icon in-game) are still played at their
regular speed, to avoid music sync issues.
TRANSLATION: Add the new translatable game file in the groovie engine
README: Update documentation on the recently changed t7g movie speed settings
NEWS: Mention the change in the movie speed options of the 7th Guest
MT-32: Sync with the latest changes in munt

This syncs our code with munt commits 3f0db2d and 2c5f314
GUI: Improve the description of the Roland GS mode checkbox
TOLTECS: Cleanup
TOLTECS: Fix menu colors
NEWS: Mention sync with the latest munt snapshot
TOLTECS: Fix more menu colors
TOLTECS: Some more menu color fixes
TOLTECS: Add an option to use the ScummVM save/load screens
TRANSLATION: Add the new translatable files in the toltecs engine
TOLTECS: Fix the colors of the arrows in the sound volume screen
NEWS: Mention toltecs support