resolve glyph names during validation

[cmyr]

Currently we don't resolve glyph names or classes fully during the validation pass; this means that there's a bunch of validation that we can only do during the compile pass, which complicates that code.

The original rationale for this was that it felt like duplicate work, but I've looked over some profiles and I don't think that's a huge concern, and this would let us remove a bunch of annoying validation logic from the compilation pass.