Projective geometric algebra is a real bear to figure out but I think I managed to scrounge together enough references to figure out some of the basic Motor and Rotor concepts. It's very similar to quaternion based rotations but there is a whole conceptual framework behind it that explains why all of the parts work like they do.
(Someone sent me this <https://marctenbosch.com/quaternions/> which is where this part started.) The non-PGA stuff is staying in the lib.
