Axisregistry

- Fix typo and ensure tox runs tests correctly (PR 50)

- Don't delete name IDs which are shared with the STAT table (PR 49)

- added _fvar_instance_collision function, which determines whether a family of fonts will have fvar instances which collide.
- build_vf_name_table: only use v1 name tables if fvar instances match (PR 48)

- AxisRegistry: add items method. Fixed googlefonts/gftools576 (PR 47)

- Add name builder (PR 31)
- Add illustrations (PRs 29, 30, 32 and 35)
- Reduce length of parametric axis descriptions (PR 34)
- y_transparent_descender.textproto Use depth, not height (PR 36)
- tox: use black (PR 39)

- Remove pre-processing of fallback names and simplify API