Modules : changed how gameplay_tweaks module works, use PARAM[] table.
Began work on code to detect "Porches".  Also ensure that the ROOM objects
have the correct 'is_outdoor' and 'kind' fields.
Porches : add pillars to them (at suitable junctions), and build the
ceiling as solid (not sky).
Porches : worked on detecting them in indoor and outdoors rooms.