Add previously-missed placeholder Vector/Matrix code
Add previously-missed placeholder Vector/Matrix code

This lets us use the read.py script without having to import the Blender
module, at the moment. Importing should probably be kept separate from
reading into blender, but it's convenient to share math structures if
possible.

ndevenish/Blender_ioEDM,ndevenish/Blender_ioEDM