Refactor the Map::neighbors so that it's part of pathing where it should be.

pathing.hpp

@@ -25,6 +25,7 @@ public:
   Matrix &paths() { return $paths; }
   Matrix &input() { return $input; }
   int distance(Point to) { return $paths[to.y][to.x];}
+  bool random_walk(Point &out, bool random, int direction);
 
   bool INVARIANT();
 };