Fonttools

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- [subset] Fixed subsetting of FeatureVariations table. The subsetter no longer drops
FeatureVariationRecords that have empty substitutions as that will keep the search
going and thus change the logic. It will only drop empty records that occur at the
end of the FeatureVariationRecords array (1881).
- [subset] Remove FeatureVariations table and downgrade GSUB/GPOS to version 0x10000
when FeatureVariations contain no FeatureVariationRecords after subsetting (1903).
- [agl] Add support for legacy Adobe Glyph List of glyph names in ``fontTools.agl``
(1895).
- [feaLib] Ignore superfluous script statements (1883).
- [feaLib] Hide traceback by default on ``fonttools feaLib`` command line.
Use ``--traceback`` option to show (1898).
- [feaLib] Check lookup index in chaining sub/pos lookups and print better error
message (1896, 1897).
- [feaLib] Fix building chained alt substitutions (1902).
- [Doc] Included all fontTools modules in the sphinx-generated documentation, and
published it to ReadTheDocs for continuous documentation of the fontTools project
(1333). Check it out at https://fonttools.readthedocs.io/. Thanks to Chris Simpkins!
- [transform] The ``Transform`` class is now subclass of ``typing.NamedTuple``. No
change in functionality (1904).

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- [feaLib] Fixed ``AttributeError: 'NoneType' has no attribute 'getAlternateGlyphs'``
when ``aalt`` feature references a chain contextual substitution lookup
(googlefonts/fontmake648, 1878).

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- [feaLib] If Parser is initialized without a ``glyphNames`` parameter, it cannot
distinguish between a glyph name containing an hyphen, or a range of glyph names;
instead of raising an error, it now interprets them as literal glyph names, while
also outputting a logging warning to alert user about the ambiguity (1768, 1870).
- [feaLib] When serializing AST to string, emit spaces around hyphens that denote
ranges. Also, fixed an issue with CID ranges when round-tripping AST->string->AST
(1872).
- [Snippets/otf2ttf] In otf2ttf.py script update LSB in hmtx to match xMin (1873).
- [colorLib] Added experimental support for building ``COLR`` v1 tables as per
the `colr-gradients-spec <https://github.com/googlefonts/colr-gradients-spec/blob/main/colr-gradients-spec.md>`__
draft proposal. **NOTE**: both the API and the XML dump of ``COLR`` v1 are
susceptible to change while the proposal is being discussed and formalized (1822).

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- [cu2qu] Added ``fontTools.cu2qu`` package, imported from the original
`cu2qu <https://github.com/googlefonts/cu2qu>`__ project. The ``cu2qu.pens`` module
was moved to ``fontTools.pens.cu2quPen``. The optional cu2qu extension module
can be compiled by installing `Cython <https://cython.org/>`__ before installing
fonttools from source (i.e. git repo or sdist tarball). The wheel package that
is published on PyPI (i.e. the one ``pip`` downloads, unless ``--no-binary``
option is used), will continue to be pure-Python for now (1868).

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- [varLib] Added support for building variable ``BASE`` table version 1.1 (1858).
- [CPAL] Added ``fromRGBA`` method to ``Color`` class (1861).

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- [designspaceLib] Added ``add{Axis,Source,Instance,Rule}Descriptor`` methods to
``DesignSpaceDocument`` class, to initialize new descriptor objects using keyword
arguments, and at the same time append them to the current document (1860).
- [unicodedata] Update to Unicode 13.0 (1859).