Add Proj.4 wrappers as an example of GeoAPI implementation

Create bindings to the C/C++ Proj.4 library using Java Native Interface, and encapsulate those bindings in a GeoAPI implementation. The GeoAPI implementation is placed in the public domain in order to encourage vendors to use it as a starting point for their own product without any legal constraint. The C/C++ code created for this task is given to the Proj.4 project and included in the Proj 4.8.0 release (in release candidate phase as of March 9, 2012). The GeoAPI binding is provided in the geoapi-proj4 module.