Gftools

Changes since previous release:

- push: add missing return 661

Changes since previous release:

- builder: Add option to interpolate between masters for static fonts. 657
- fix: return a new TTFont instance for fix_font and fix_family 659

Changes since previous release:

- gen-push-lists: fix args 652
- publish-release: use build 653

Changes since previous release:

- Sync fonts_public.proto with internal 629
- Support glyphspackages 630
- Update link to new GF Guide 631
- Remove mentions of apputils, fixes 41 632
- Only upgrade OS/2 tables v2+, fixes 550 636
- Skip directories from the push lists if their parent is also present 637
- Refactor binaries into packages 638
- Add fields to fonts_public.proto so we can delete upstream.yaml 639
- add-axis: do not include fallbacks 641
- qa: Use diffenator2 643
- Fix closure handling of ufomerger 647
- Stop removing the MVAR table 648

Changes since previous release:

- push: add more path transforms 625
- set protobuf to use same versions as fontbakery 626

Changes since previous release:

- Add Knowledge protos 621