v1.2.1

• Implemented Flatbush with all basic APIs, including the indexing (add, finish) and the searching (search, neighbors).
• Implemented Geoflatbush extension for geographic queries, which exposes the around API which is the equivalent of neighbors but curvature and dateline wrapping aware.

This was ported from Volodymyr Agafonkin's flatbush and geoflatbush, it is such a handy tool and I can't thank him enough for having created it!