Making the blender_cloud.pillar and blender_cloud.cache modules usable
without Blender required some moving of the code, from __init__.py to
blender.py.
CacheControl requires the lockfile package, which increases the number
of bundled wheel files to 3. Those are now managed by
blender_cloud.wheels.load_wheels(). The wheels are only loaded if the
Python installation doesn't yet contain the required packages. This allows
development with virtualenv-installed packages, debugging in the IDE, etc.
This uses Reqests-Cache, which should be installed on the PYTHONPATH or
provided as a wheel in blender_cache/requests_cache-*.whl. In the latter
case, it'll be automatically added to sys.path.
The 'cancelled' status is now tracked by a Future that's passed to
different asychronous tasks. That way it is possible to cancel all
running tasks before browsing another Pillar node.
We now draw the GUI using OpenGL in Python. This allows for much more
control on the Python side. It's still a prototype, and allows us to
test the features without depending on C support in Blender itself.
GUI code was taken from the Asset Flinger addon.
