Fix static map key gen for invalid rooms (#42)

Flood fill now detects rooms that cannot have access levels,
e.g. rooms must be contiguous blocks of room tiles
surrounded by wall tiles and at least one door tile, which
leads to a floor tile.

Doors that connect rooms both with access levels now
take on the access level of the more secure room.

Update techdemo/static.cpn to contain a mission with
lots of connected rooms