Extends the SquareGridWGMap. Creates a ‘maze map’ in which players gain bonuses for completing a row or column
adds a maze starting at r,c if r & c are -2, a territory with no borders is found (if it exists), and the random walk is started there. otherwise if r or c is negative, they are set to the middle of the map.
todo: This seems to hang on a rare occasion (recursion to infinity). What is happening? Does it get stuck in a corner somehow?