Moved distance limiting code to a smarter location, refactored related code

graph.h

@@ -14,6 +14,9 @@ using std::list;
 class Vertex
 {
   public:
+    Vertex(int x, int y)
+    { this->x = x; this->y = y; }
+
     int x;
     int y;
     int x_min;
@@ -44,6 +47,8 @@ class Graph
     void do_vertex(int x, int y, int size);
     Vertex* get_current_vertex() { return current_vertex; }
 
+    static int MAX_MOVE_DISTANCE;
+
  private:
     void add_vertex(int x, int y, int size);
     void select_vertex(int x, int y);