Rest angle for dualHingedRigidBodyStateEffector

[JoMeMi]

Hi!

To have the opportunity of simulating solar panels as either stowed or deployed as well as simulating the actual deployment of solar panels, the resting angle theta_0 in the nHingedRigidBodyStateEffector is the perfect choice. The resting and initial angle can be set differently whether the panels should start the simulation as stowed or deployed. Using an event, the resting angle can be set to something different during a simulation to simulate the release of a HDRM. However, this variable does not exist in the dualHingedRigidBodyStateEffector, so my idea is simply:

• Add theta_0 in the dualHingedRigidBodyStateEffector