Created by: aperloff
Allow the transformation of vector<vector> branches to be saved as flattened vector branches with an associated vector branch of offsets.
Two unit tests were performed, one keeping the nested vector format and the other flattening the vectors. Flattening the vectors has the effect of decreasing the ntuple size by a little under 1% (0.88% in our 100 event test).
I have not tested the speed change.