accept geopandas input

[knaaptime]

several of the key functions (set, set_pois, get_node_ids) take x,y coordinates as arguments, but in practice the data is almost always coming from a geodataframe. It might be nice to add a handler underneath so these functions could just take a geodataframe/series instead. So when adding a new variable on a network, you just pass in a set of [destination] points instead of calling get_node_ids and set in sequence.

Thus, when get_node_ids is called with a geometry object, it passes the x,y coords off appropriately (downcasting to centroids if necessary). When set/set_pois is called with a geometry input, it calls get_node_ids internally and sets the variable from the points rather than a list of node_ids