Linalg refactor

[Korijn]

Goal of this issue is to be provide a more pythonic API and to make it easier to track changes to world object transforms.

• Start using the https://github.com/pygfx/pylinalg package so we can drop the linalg module and tests from this project.
• Refactor such that we work with plain ndarrays for all data (e.g. vectors, matrices, quaternions)
• Provide modules with linalg utils (e.g. pylinalg.quaternion.from_euler())
• Be consistent about functions accepting arguments: xx(point) vs xx(x, y, z). Also in the pygfx itself.
• Be able to add and multiply vectors, and be able to scale (interpolate) rotations.
• In-place ops ...

[almarklein]

This can be useful: https://www.python.org/dev/peps/pep-0646/

[almarklein]

Korijn is working on it: https://github.com/pygfx/pylinalg/pull/5