Initial geo-region coder

This implements an initial cut of the core class, a SpatialIndex, used to do geo-region coding.  It can find the feature ID corresponding to the geo feature that completely contains (including boundaries) a point or any other geometry.

Also included:
- unit test
- performance benchmarking tool
- sample data/shapefile
NvM, I just remembered that we are sending in the points and not the dataset, so the suggestion above isn't really appropriate.