Added Peter's instruction timing tests to TestMultibodyPerformance, plus some extras.
Added Peter's instruction timing tests to TestMultibodyPerformance, plus some extras.

elen4/simbody,simbody/simbody,Gjacquenot/simbody,chrisdembia/simbody,Gjacquenot/simbody,scamille/simbody,Gjacquenot/simbody,chrisdembia/simbody,elkingtonmcb/simbody,chrisdembia/simbody,elkingtonmcb/simbody,elkingtonmcb/simbody,robojukie/simbody,simbody/simbody,scamille/simbody,elen4/simbody,scamille/simbody,robojukie/simbody,robojukie/simbody