Removed a dependency on the higher level specifying a target angle to give correct torque calculations
Our model of hydraulic flow's dependence on joint torque was causing the sim to go unstable.  For now I've removed the flow's dependence on joint torque.  We may be able to get around the stability issues with a low-pass in the torque->flow conversion, try it later.
Added support for controllers with a graceful exit callback.  The whole structure of importing controllers should be revised... I'd like to see them inherit from a base class instead of just having the right attributes in the module
Manual merge