Speed up diff.

[typesupply]

• optionally pass a GLIF vendors to diffFont and compare the raw text before getting into the object. if the text matches, don't parse. if the text doesn't match, parse and do the comparison. dict-like object glif = vendor[layerName, glyphName].
• allow specifying specific glyphs, layers to test.
• allow specifying glyphs, layers not to test.
• make group, kerning, etc. optional.