add SetCharAt to ShortString
add SetCharAt to ShortString

cvmfs/cvmfs,Gangbiao/cvmfs,djw8605/cvmfs,Gangbiao/cvmfs,djw8605/cvmfs,DrDaveD/cvmfs,DrDaveD/cvmfs,cvmfs/cvmfs,trshaffer/cvmfs,djw8605/cvmfs,trshaffer/cvmfs,Gangbiao/cvmfs,trshaffer/cvmfs,djw8605/cvmfs,DrDaveD/cvmfs,cvmfs/cvmfs,DrDaveD/cvmfs,DrDaveD/cvmfs,Gangbiao/cvmfs,cvmfs/cvmfs,djw8605/cvmfs,trshaffer/cvmfs,DrDaveD/cvmfs,cvmfs/cvmfs,cvmfs/cvmfs,DrDaveD/cvmfs,Gangbiao/cvmfs,cvmfs/cvmfs,trshaffer/cvmfs