Add calo branches

[giro94]

Adding calorimeter branches: clusters, hits, recodigis.

Plan is to have separate branches for each struct type.
Clusters will have vector of indexes of hits.
Hits will have vector of indexes of recodigis.
Hits (digis) will have a single index of the cluster (hit) they belong to.

[giro94]

Branch now properly fills calo cluster, hits, and recodigi branches.
Each branch links with both the parent and child branches with indexes.

[AndrewEdmonds11]

Thanks for this, Paolo! It all looks OK to me. Would you mind also doing step 8 and the first part of step 11 of these instructions to add the new branches to the ntuplehelper?

We can discuss who does what in the other steps but that can all be done in a separate PR

[sophiemiddleton]

I'm happy with the code just by eye, i'd like to test it just to get a feel for the new branch

[giro94]

The calo branch filling code in EventNtupleMaker is a bit ugly and 100+ rows long.
It's functional, but I will chop it up into dedicated functions later.

[AndrewEdmonds11]

Thanks for making the changes to ntuplehelper, Paolo. As we discussed on Slack, I will look into the bug related to that