Cityseer

Removes zero-length self-looped edges if encountered in `nX_simple_geoms`

This resolves a situation where a converted OSM graph with a zero length edge causes downstream errors. This arises because inferring geometry for a looped OSM edge (same start and end node) implies a zero-length geom: this results in `geometry.Point` instead of `geometry.LineString`. These zero-length edges are now removed.

Updates setup.py.

- Adds `primal_node_size` and `dual_node_size` parameters to the `plot_nX_primal_or_dual` function.
- Adds a `node_size` parameter to the `plot_nX` method.
- Updates docs.

Flips signs of beta formulations for negative exponential weights with the implication that beta values should now be provided as positive floats instead of negative floats.

- Adds a function for converting `OSMnx` `multiDiGraph` to `cityseer` compatible `MultiGraph`.
- Adds docs providing context on comparison to `OSMnx` and other graph packages.

Bumps version to v1.0.0 so that pre v1 versions are not installed by default via Pip.