feat: added geometric combine rule and examples

[Evanev7]

Closes issue #685. I'm getting some crashes on an example I haven't touched - Multibody joints 3d crashes under the parallel,simd-stable feature set with Matrix slicing out of bounds.

Should I open a new issue for this separately?

Otherwise, I think this is the expected implementation of this feature. If this is all good I'll try tackle a harder issue next!