Some fixes to atlasing where the original texture is too small or wraps
hash function for vector4's
Properly use texture coordinate from the target collapse vertex
In AggregateManager, various bug fixes as well as:
- Deduplicate meshes only if they are very small in the overall aggregate (don't want to replace large objects that make up an aggregate)
- Do not deduplicate if the two meshes cannot be aligned using their major and minor axes
- Use a lock to protect the shared state across threads downloading textures before atlasing.
- Better management of the in-memory mesh store in Aggregate Manager
While exporting collada, skip any empty texture names in texture list.