Better campaths based on B-Splines in R³ and SO(3)

[dtugend]

It's possible to do a lot with B-Splines, think from user perspective (which think in terms of connected path segments) for the requirements.

B-Spline:

• https://en.wikipedia.org/wiki/B-spline
• A General Construction Scheme for Unit Quaternion Curveswith Simple High Order Derivatives, Myoung-Jun Kim, Myung-Soo Kim, and Sung Yong Shin, Korea Advanced Institute of Science and Technology (KAIST), Pohang University of Science and Technology (POSTECH)
• https://github.com/tbriand/bspline_interpolation_c (only supports natural boundary conditions though, which is not enough for us)
• https://github.com/msteinbeck/tinyspline

See also

• Loop campaths / camio #156 Loop campaths / camio
• Campath time smoother™ #223 Campath time smoother™
• Replace / Visualize Quaternions with Rotors in GUI? #696 Replace / Visualize Quaternions with Rotors in GUI?

[dtugend]

The implementation of this feature in a reasonable time-frame is currently not realistic for me. After considering that together with issue #896 I am closing this request as not planned for now, since it would block other things I would like to still get done before that. Sorry for the copy pasta.