64bc6d27b2
Added analytic derivatives of smooth (unconstrained) dynamics forces, with respect to velocities: - Centripetal and Coriolis forces computed by the Recursive Newton-Euler algorithm. - Damping and fluid-drag passive forces. - Actuation forces. A new implicit-in-velocity integrator is implemented using the analytic derivatives. This integrator lies between the Euler and Runge Kutta integrators in terms of both stability and computational cost. PiperOrigin-RevId: 450377010 Change-Id: Ie192b441876c22e732fb749333926f296e0a09cc