Add NetCDF wrappers as an example of GeoAPI implementation

Add wrappers around the UCAR NetCDF library as an example of GeoAPI implementation. Those wrappers are placed in the public domain in order to encourage vendors to use it as a starting point for their own product without any legal constraints. The initial draft of those wrappers will provide only basic coordinate transformation capabilities. Future versions should provide some coverage support.

Those wrappers are available in the geoapi-netcdf module.