Dataset now does not have a location by itself, but is only a container for `DataItems`.
Fixing admin according to model changes.
Fixing format readers to return multipolygons instead of polygons. Fixing Dimap format, most of the values are optional. Updated tests aswell.
Implemented metadata extraction from gdal datasets.
Further work on registration script. Needs some work for finalization.
Set maximum character length for EOObject identifiers to 256. Implemented easier iteration over bands in a range type. Implemented size setter for coverages.