compatibility:
- added subpackage 'python' for handling compatibility issues between python versions

geo.raster.conversion:
- revised raster2polygon(): added timeout, progress bar, quiet mode

io.raster.GeoArray:
- added progress keyword
- nodata: bugfix
- footprint_poly: now returns outer box if raster2polygon timed out
- show(): bugfix for crash in case input image has only one value
- show_map(): bugfix for crash in case input image has only one value

processing.progress_mon:
- added function is_timed_out()
- printProgress(): added timeout keyword