Removed obsolete and/or experimental classes, in particular the 2D
rendering packages and related classes like sprite data files, parsers
and processor classes. These are moved to the tetragon-obsolete
repository (https://github.com/hexagonstar/tetragon-obsolete) because
the 2d rendering system (which wasn't fully implemented) is being
re-concepted and re-implemented. The removed classes are beinmg put on
the obsolete repositiry as a back-reference for the new rendering
system.