Fix a few bugs to get the visualizer prototype functional on Windows.
Fix a few bugs to get the visualizer prototype functional on Windows.

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