Removed hardcoded dt in PhysicsManager
Removed hardcoded dt in PhysicsManager

For some reason dt is hard coded to 1ms in the PhysicsManager::doUpdate
function instead of using the dt passed into doUpdate. Since the
manager's rate is already set to 1000Hz, dt is already correctly passed
to doUpdate as 1ms.

simquest/opensurgsim,simquest/opensurgsim,simquest/opensurgsim,simquest/opensurgsim