Added a parser for GeoJSON whose type is unknown until runtime
Corrected TODO style and added missing explicit keywords for 1-arg ctors
Fixes indentation/whitespace, inlines short methods, removes explicit keyword on copy constructors, reorders static method declarations, removes commented out code, and adds a missing /** @file */ header.
Dropped the GeoJSON prefix from everything, moved all code from /geojson into /geo (because Coordinates2D is actually not GeoJSON), added namespaces mongo::geo, mongo::geo::coords2d, and mongo::geo::coords2dgeographic, cleaned up demo, fixed some style issues, fixed some ownership issues. There are still more ownership issues to address for next commit.