Completely rewritten mass matrix computation for IGA beams. Tested and validated.
Completely rewritten mass matrix computation for IGA beams. Tested and validated.

rserban/chrono,rserban/chrono,Milad-Rakhsha/chrono,projectchrono/chrono,dariomangoni/chrono,rserban/chrono,projectchrono/chrono,Milad-Rakhsha/chrono,dariomangoni/chrono,dariomangoni/chrono,dariomangoni/chrono,projectchrono/chrono,dariomangoni/chrono,Milad-Rakhsha/chrono,Milad-Rakhsha/chrono,Milad-Rakhsha/chrono,rserban/chrono,rserban/chrono,projectchrono/chrono,projectchrono/chrono,rserban/chrono,dariomangoni/chrono,projectchrono/chrono,Milad-Rakhsha/chrono,rserban/chrono