Added image scene to render an image in a scene. There is also now
a testing image that is an uber meme. Currently the problem is
that the spritebatch cannot use the offsetof macro because it is a
templated class. Possible solutions to this are changing it to be
specifyable or implemented per vertex type as the other batches
have been.
Also added a required prerender function to scene and application.
This function is intended to be used as a way to prepare the scene
to be rendered in its current state. For that reason, the delta
time and the current clock tick are not passed to it.
Finally got a 3D cube to be rendered. While doing it, fixed a
bug in MeshFactory that caused it to allocate the incorrect amount
of memory for each mesh.
