restructure puzzle space generation (for boards up to 5x5)

- uses a huge global seen-states-cache. Not scalable without more
filtering

include/orbit_camera.hpp

@@ -24,8 +24,7 @@ public:
 
     auto pan(Vector2 last_mouse, Vector2 mouse) -> void;
 
-    auto update(const Vector3& current_target, const Vector3& mass_center, bool lock,
-                bool mass_center_lock) -> void;
+    auto update(const Vector3& current_target, const Vector3& mass_center, bool lock, bool mass_center_lock) -> void;
 };
 
 #endif