Remove unused 'set_empty...' functions
Remove unused functions, move long regional names to datapointapi
Move log() into utilities
Clarify operation of filter_sitelist
Move filter_sitelist, clean_sitelist into datapointapi
Rename datapointapi -> datapoint
Move icons into skin
remove sys.path butchery
remove unused addon properties
remove uv colour coding
remove unused _ICON variables
Remove unused visibility codes.

Should be moved into skin if ever reactivated.
Rainfall Forecast Maps added