Setup basic tests for wall carving

src/Dodge/LevelGen/StaticWalls.hs

@@ -48,6 +48,8 @@ checkWallLeft (x,y) wls = case filter (\(a,b) -> b == x ) wls of
 -- given a polygon of points and collection of walls, cuts out the polygon
 -- ie returns a new set of walls with a hole determined by anticlockwise ordering of the points
 cutWalls' :: [Point2] -> [WallP] -> [WallP]
+cutWalls' [] walls = walls
+cutWalls' [x,y] walls = walls
 cutWalls' qs walls = 
 --    nub
 --    . filter (not.wallIsZeroLength)