v 0.2.17 - max speed

Minor changes:

Added nocache parameter to dodgr_contract_graph, to enable forced re-calculation of contracted graphs (#194)
Fix bug in graph contraction which prevented in picking up additional data columns (#194; thanks to @sriramab)
Fix bug in caching mechanism which stopped graph conversion routines (like dodgr_to_sf) from carrying across extra columns (#194; thanks to @sriramab)
Fix bug in distances when from or to default to all vertices
Fix weighting networks for motorcars to adhere to OSM "maxspeed" values where those are given, rather than profile values (#193)