Major updates to the IGA beam. Now it is working OK. There are some remainig features, but the bulk of the work is done. Important news: - the internal force computation has been split in ComputeInternalForces(), which uses the current state, and ComputeInternalForces_impl(), that uses a generic state. - the internal force computation had some bugs in rotation interpolations, now fixed - the stiffness matrix is implemented with a brute force approach, using numerical differentiation. Maybe not 100% elegant, but it works fine so far. - implemented the interfaces for ChLoadableU, for applying distributed loads, if wanted, and for helping with the stiffness matrix computation via numerical differentiation - implemented some experimental code for structural damping a-la-Raleygh, in the internal force computation. But please do not use it for the moment  (i.e. set Raleygh damping to 0) because the computation of the damping matrix is not yet in place
Major updates to the IGA beam. Now it is working OK. There are some remainig features, but the bulk of the work is done.
Important news:
- the internal force computation has been split in ComputeInternalForces(), which uses the current state, and ComputeInternalForces_impl(), that uses a generic state.
- the internal force computation had some bugs in rotation interpolations, now fixed
- the stiffness matrix is implemented with a brute force approach, using numerical differentiation. Maybe not 100% elegant, but it works fine so far.
- implemented the interfaces for ChLoadableU, for applying distributed loads, if wanted, and for helping with the stiffness matrix computation via numerical differentiation
- implemented some experimental code for structural damping a-la-Raleygh, in the internal force computation. But please do not use it for the moment  (i.e. set Raleygh damping to 0) because the computation of the damping matrix is not yet in place

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