Cityseer

Resolves an edge case in graph consolidation workflows where a new node is located on top of an existing node.

Repurposes `io.osm_graph_from_poly_wgs` to `io.osm_graph_from_poly`:

- The input polygon's projection no longer has to be `4326` WGS, though this remains the default. It is now possible to specify other EPSG codes, e.g. `27700` if working with BNG.
- A `to_epsg_code` parameter has been added for specifying the output EPSG code. This is an optional parameter, and the behaviour will default to the local UTM CRS as per previous behaviour. If specified, the generated street network will be returned in the specified CRS.

Adds `nx_epsg_conversion` for converting networks from between specified EPSG CRS codes.

Refreshes docs and examples accordingly.

Minor tweaks and edge case handling in graph cleaning methods.

Adds continuity metric for "names", "routes", "highways" continuity, and a hybrid "names" and "routes" continuity.

Examples using OSM and OS Open data added to the [examples](https://cityseer.benchmarkurbanism.com/examples) page.

Addresses Shapely deprecation warnings for STR trees by adopting the new API.

Moves demo notebooks plots into cityseer.plot module.

This is to simplify use of the functions when running notebooks.

- moves osm related import and conversion functions to the new io module
- creates a new io function for importing open roads data