new I3MCTree

git-svn-id: http://code.icecube.wisc.edu/svn/projects/clsim/trunk@126486 16731396-06f5-0310-8873-f7f720988828
cleaner implementation of things regarding daughters

git-svn-id: http://code.icecube.wisc.edu/svn/projects/clsim/trunk@126573 16731396-06f5-0310-8873-f7f720988828