Siibra

**Full Changelog**: https://github.com/FZJ-INM1-BDA/siibra-python/compare/v0.3a10...v0.3a11

**Full Changelog**: https://github.com/FZJ-INM1-BDA/siibra-python/compare/v0.3a9...v0.3a10

**Full Changelog**: https://github.com/FZJ-INM1-BDA/siibra-python/compare/v0.3a8...v0.3a9

- Qualifications and descriptions of feature links to brain regions, see examples/03_data_features/000_matchings.py
- Basic support for surface meshes
- remove dependency to cloud-volume in favor of the much more lightweight neuroglancer-scripts
- first implementation of EbrainsPublicDatasetConnector for querying versioned files from datasets in the new EBRAINS Knowledge Graph V3, used for new connectivity datasets (https://github.com/FZJ-INM1-BDA/siibra-python/blob/ff2048d952299b2a8594108c2318d92c0c22f6be/siibra/retrieval/repositories.py#L264)
- first implementation of EbrainsHdgConnector for getting data from the EBRAINS Human Data Gateway (https://github.com/FZJ-INM1-BDA/siibra-python/blob/ff2048d952299b2a8594108c2318d92c0c22f6be/siibra/retrieval/repositories.py#L174)
- many smaller fixes and updates

- almost full rewrite of documentation with real code snippets from examples/ using sphinx-gallery
- Refactor of `ContinuousParcellationMap.assign()` and unify with `assign_coordinates()`; now returns a pandas dataframe
- bring back cell distribution features (fix species spec)
- several bug fixes
- first implementation of a bigbrain sampler