That was a Blender thing. Also updates the process-model
script so that it runs some stuff in parallel, which might
make it slightly less agonizingly slow.

(just a credit card for now, though). This also introduces some fixes
to the process-model script, allowing for it to compensate for the
extra height introduced by the line art. blender-model.py is adjusted
to allow for this, and makeModel() now checks for the bottom/extra
values produced by the process.