fileout_gdal seems to build broken JP2k files

Lookng at the code in FONgTransform, it may be that it should be modified to follow the pattern used for the GeoTIFF code (instead of writing the info to a MEM object and then using CreateCopy to make the JP2k file, use the recipe that is used for GeoTIFF).

Also:

• There are two copies of the return_temp_stream() method - one for the GeoTIFF code and one for the JP2k code. This should probably be turned into a utility function in the BES.

• The tests for the JP2k output are pretty weak