changed decayTopology to fix genPseudoData.py

Since the implementation of the eventFileWriter into genPseudoData.py the
arguments of decayTopology's methods (which took ROOT Objects) were
impractical. Changed the Python wrapper as well as the source files to
reflect the new handling. The changes in genPseudoData were minor.
Merge branch 'usrIface' of github.com:odrotleff/ROOTPWA into usrIface