Also lets models have a default view for each form. Fixes some incorrect
behaviors with the setup of entities to go along with this (e.g. if there
was no default form, the last form would wind up being the default, rather
than the first, if default views were specified.

The importer reads a directory of .zip files and imports each one to its own collection.

Instead of using the built-in camera fitting function,
which wants to rotate the camera, it now calculates the
local bounding box of the object for each camera angle.

This uses a new 4-color scheme. Wow.

Inkscape now exits before it finishes writing its files, somehow.
So, we need to wait for the files to be created. The Blender
add-on also now correctly configures the lineart to use the
secondary camera, which is rotated to avoid errors when rendering
orthographically.

Also update the add-on to allow for configuration of
potrace's alpha settings, which controls how strongly
it favors straight lines. This makes things like buildings
look a lot nicer.

Also, modify the Blender add-on so that mass can be
computed via density even if a volume is not being included

Also update the add-on a bit to fix some errors

Also update the scripts to support tagging entities
with masses and volumes.

Also updates the add-on some more. It can now
assign materials based on face maps, which the
Building Tools add-on creates automatically