Glyphslib

- Customize the ufo2ft's featureWriters by setting a key in the generated designspace `<lib>`. This is necessary in order to keep the current behavior in light of an upcoming change in the `KernFeatureWriter` default mode which is planned for the next ufo2ft release (441).

- parser: no longer accept invalid comma-separated lists of unicode values which are not wrapped within quotes (436).

* More robustly handle public.glyphOrder: It is now generated/recovered in the way Glyphs.app expects it, leading to fewer differences when round-tripping. See https://github.com/googlei18n/glyphsLib/commit/11d11110a9c191b80fa57782738b8e76053f43e4 for details.
* Glyph classes are now always placed at the top of generated feature files: custom lookups are usually placed in the "Prefix" of a .glyphs file and may use these classes. Previously, classes were placed after them, breaking them.
* Fix parsing backslash escaped glyph names in features. Fixes https://github.com/googlei18n/fontmake/issues/445.
* A `GDEF` table is now only generated by `glyphs2ufo` if you pass the `--generate-GDEF` argument. The `GDEF` table should only be generated if you are generating final binaries and may need the `--propagate-anchors` argument to work properly.
* Make sure fontMasterID lib keys in UFOs are unique and error out otherwise. This can happen if you make a new master outside Glyphs.app.
* Italic masters aren't named "Regular Italic" anymore.

- [axes] Fixed issue when 'Axes' custom parameter is defined but not all the masters contain a 'Axis Location' custom parameter (409, 411, 416).
- [kerning] Round-trip kerning pairs as they are between UFO and glyphs, without performing any conflict resolution (best left to compiler) (407).
- [glyphs2ufo] Made normalization of UFOs opt-in, instead of opt-out. Use `-N` or `--normalize-ufos` to enable this from the command line script. Requires the ufonormalizer module (415).
- [glyphdata] Embed GlyphData.xml And GlyphData_Ideographs.xml as package data files and parse them at run-time. Removed `glyphdata_generated` module. Expose 'script' and 'description' attributes of GlyphData database (410).
- [parser] Always return list of hex strings when parsing `unicode` attribute (405, 95dd3cd).
- Added pre-commit hooks configuration and automatic linting and code reformatting to the CI checks. Reformatted the whole codebase with black. Fixed a few flake8 linter issues (414).

- Correct handling of codePageRanges
- UFO's openTypeOS2CodePageRanges has a few bits that Glyphs doesn't support, save those to a custom parameter on round-tripping.
- Empty openTypeOS2CodePageRanges lists stay empty instead of being removed.
- Fix openTypeOS2Selection handling
- Store unsupported bits in a openTypeOS2SelectionUnsupportedBits custom value on round-tripping
- Empty lists are preserved on round-tripping
- openTypeOS2Selection will be sorted
- Properly handle categorization of glyph variants
- Non-spacing marks are properly categorized. This helps with proper feature building and zeros their width.
- Handle not only matches for full glyph names, but also ligatures and glyph
variants. Opportunistically concatenate uni* values.
- Comment the code better.
- Round-trip italicAngle == zero
- glyphs2ufo: Make creating background layers optional (off by default)

Fix a crash when round-tripping a GSFeaturePrefix containing only a comment

Fixed 'ImportError: no module named interpolation' in fontmake
googlei18n/fontmake451