Define data structure to use in a BEM

[carlos-adir]

Need adding the data structure for cases when BEM is used.

Main points

• For Torsion and Shear, discretization of boundary is necessary
• For geometric, axial force or bending, such discretization is not necessary

Since every Jordan Curve is already parametrized, an idea is to use a vector of floats meaning the breakpoints.
With that, no control points are added in the original model