Initial stab at pulling the pathing out.

pathing.hpp

@@ -0,0 +1,25 @@
+#pragma once
+#include "map.hpp"
+#include "point.hpp"
+
+class Pathing {
+public:
+  int $limit;
+  size_t $width;
+  size_t $height;
+  Matrix $paths;
+  Matrix $input;
+
+  Pathing(size_t width, size_t height, int limit) :
+    $limit(limit),
+    $width(width),
+    $height(height),
+    $paths(height, MatrixRow(width, 1)),
+    $input(height, MatrixRow(width, 1))
+  {}
+
+  void compute_paths(Matrix &walls);
+  void set_target(const Point &at, int value=0);
+  void clear_target(const Point &at);
+  bool INVARIANT();
+};