Untangling - step toward librarization

This PR doesn't yet move GeometryCache and TextureCache into a library, but it does untangle them from Application and reduce dependencies between GeometryCache and Model.
Well yeah, now that I think of it a Hash might note be the best thing. It's fast but not instant.
Wich is why I think I"ll change how it works internally so that everything is resolved at compile time. that way it should be instant.