Added paramter tgt_coordgrid to to_map_geometry methods to automatically move...

Added paramter tgt_coordgrid to to_map_geometry methods to automatically move the output extent to a given coordinate grid.
compute_areadefinition_sensor2map() now also adds 1 pixel around the output extent in the pyresample version just like in the GDAL version.

Signed-off-by: Daniel Scheffler <danschef@gfz-potsdam.de>