Add quadratic B-spline shape functions

This MR adds the quadratic B-spline shape functions feature as implemented in geomechanics/mpm by Soga Research Group. It also adds a option for saving the shape functions into a CSV file.

I tested these changes both on a pure MPM oedometric test simulation using Hooke's law, and on a pure MPMxDEM granular column collapse settling using Mohr-Coulomb model. The results are the ones expected, i.e. better results than with linear shape functions (the stress is not constant within a mesh cell). Although, the GCC settling simulation took considerably longer with B-spline shape functions (~ 75x longer).

Results of the GCC settling with linear shape functions (~ 42 s)

Results of the GCC settling with quadratic B-spline shape functions (~ 53 min)

Note: I'm not sure why the feature saving the shape functions didn't save a point for x=1 m, but I think this is not problem since it only concerns post-processing.

Mesh nodes