Standardize handling of glyph names for U. F. O. output.

This adds a standards-compliant name mangler and a hash table look-up for glyph names (so that we can iterate names that collide after mangling).

@JoesCat, @jtanx, I'm sort of eager to solve the .gitmodules problem, but I don't know much about bootstrap. Does either of you have any insight here before I dive in?