added some constants; changed references to MKS units to SI instead
added some constants; changed references to MKS units to SI instead

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