Ray pick sub meshes

* implements Model::findRayIntersectionAgainstSubMeshes() which will ray pick against the individual AABox's of the submeshes of the model and if those meshes belong to named models, return the name of the model the mesh belongs to.
* includes example script for prototype lobby with model overlays
* Moves RenderArgs out of octree library and into shared so it can be used by overlays
* fixes bug in Model::scaleToFit() which wouldn't allow you to scale to fit to a single dimension unless the model was active