Remove NTS dependencies from tests.

After removing the GeoAPI / NTS dependencies from the main project, NTS uses were limited to:
- A few old tests that could easily be rewritten to no longer use Coordinate objects
- Performance tests left over from when we were deciding how to implement bulk transformation (but turned into an exercise in testing the performance of the test code itself instead of anything in ProjNET)
- A convenient way to read a bunch of coordinate values (but we can just save the raw coordinate values themselves to get even bigger bulk transform performance tests)

Author: airbreather