Add support for compressed, and embedded GDAL support data files.
As we distribution more coordinate system dictionaries with GDAL (such as the mooted IAU dictionary), it becomes apparent it would be desirable if these could be read directly from compressed files instead of having to be decompressed.
In the case of the IAU file, a 1MB uncompressed file, is 24K compressed due to the high degree of redundancy.
It would also be desirable (as previously expressed) if GDAL data files could be built into the DLL to reduce path finding complexity as an option. It would be best if the built-in version was compressed.