Graphicle

Patch: fixed over-eager `graphicle.select.vertex_descendants()` including background particles incident on the same hadronisation vertex as the descendants.

Change log:
- added autogenerating API documentation
- added initialisation classmethod for `graphicle.Graphicle` objects from `event` objects which satisfy the `graphicle.base.EventInterface` protocol, _eg._ `showerpipe` and `heparchy` events
- added `graphicle.calculate.azimuth_centre()` to calculate the centre of a particle set's `phi` position

Improvements to `MaskGroup`:
- repr uses quotation marks for keys
- Subclasses `collections.abc.MutableMapping` to provide dictionary-like interface

Documentation updates.

No longer backwards compatible with Python<3.9.

- Added ability to calculate the inter-particle delta R values from two arbitrary `MomentumArray`s, by using `MomentumArray.delta_R`.
- Removed dependency on scikit-hep's Vector library.
- Breaking changes: removed `phi_pol`, `eta`, `phi` from calculate module. This functionality is now migrated to `MomentumArray`.

Added wrapper to FastJet's generalised kt algorithm to calculate module.

Type annotation updates, and patches for `AdjacencyList.from_matrix()`, and `calculate.phi()`.

**Full Changelog**: https://github.com/jacanchaplais/graphicle/compare/0.1.2...0.1.3