Show splines in other (weird) vector spaces

[mgeier]

For now, we mostly show examples in Euclidan space, but the equations should work with any vector space.

For example, the polynomials of a given degree also form a vector space. And matrices as well.

There are already 2 examples, though:

• 4D quaternion space: https://splines.readthedocs.io/rotation/naive-4d-interpolation.html
• the 3D space of Euler angles: https://splines.readthedocs.io/rotation/naive-euler-angles-interpolation.html

Would it be possible to interpolate in the vector space of rotation matrices?