Support "disabled" glyph classes

[psb1558]

For example, features.fea in all generated UFOs has "uni0305" in "@MarkClass1" but "overlinecomb" elsewhere in features.fea and all other files.

To reproduce, run glyphs2ufo on this file (Junicode Italic).

Is this a bug, or is there something odd about this file?

[khaledhosny]

These classes are defined like this in the Glyphs file, and are not generated by glyphs2ufo:

[psb1558]

Oh, heavens, I never even looked at those because I had them disabled and assumed that glyphsLib would therefore ignore them. I will close this (with more than a little embarrassment).

But isn't it odd that glyphsLib doesn't respect the "disabled" flags in the Glyphs file? Makes it a little tricky to generate fonts while a project is in progress.

[khaledhosny]

I think #761 should fix this.

[psb1558]

Looks good.

[khaledhosny]

We need to fix handling of disabled classes, #761 does not actually handle it.