Add ChMatrix33 constructor from 2 vectors.
Add ChMatrix33 constructor from 2 vectors.

This constructs a symmetric 3x3 matrix with the specified vectors as diagonal and off-diagonal elements.

projectchrono/chrono,rserban/chrono,rserban/chrono,dariomangoni/chrono,amelmquist/chrono,armanpazouki/chrono,jcmadsen/chrono,armanpazouki/chrono,rserban/chrono,rserban/chrono,rserban/chrono,jcmadsen/chrono,dariomangoni/chrono,rserban/chrono,armanpazouki/chrono,jcmadsen/chrono,projectchrono/chrono,armanpazouki/chrono,amelmquist/chrono,Milad-Rakhsha/chrono,rserban/chrono,Milad-Rakhsha/chrono,Milad-Rakhsha/chrono,dariomangoni/chrono,amelmquist/chrono,projectchrono/chrono,armanpazouki/chrono,projectchrono/chrono,jcmadsen/chrono,jcmadsen/chrono,Milad-Rakhsha/chrono,jcmadsen/chrono,amelmquist/chrono,dariomangoni/chrono,dariomangoni/chrono,Milad-Rakhsha/chrono,dariomangoni/chrono,projectchrono/chrono,jcmadsen/chrono,projectchrono/chrono,amelmquist/chrono,amelmquist/chrono,Milad-Rakhsha/chrono,armanpazouki/chrono