Backed out change for 1771, to allow throttle operate correctly winth RD. Added
test to check for TrainBrakeController so Hy-drive does not give an exception.
git-svn-id: http://svn.uktrainsim.com/svn/openrails/trunk@1775 a9f3cfff-6c41-7446-b0ca-052bd761e6eb