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).

bootstrap successfully adds gnulib to .gitmodules even if the file exists and lacks gnulib, at least for me. But if we were to exclude gnulib from the canonical submodule list, the submodule reference would get dropped every time somebody runs checkout unless followed by bootstrap, and commit -a would pick up those new lines each time.

Aside from bootstrap, what are we using from gnulib anyway?