Follow-up from "WIP Gaudifunctional calo future merged pi0"

The following discussion from !1283 (merged) should be addressed:

• @graven started a discussion: (+2 comments)

  please update the tool interfaces such that they accept references instead of pointers, i.e. so that the code can be written as:

      sc1 = m_tagger->tagPosition(  *cl1  );
      sc2 = m_tagger->tagPosition(  *cl2  );
  

  this will make a future migration to use containers of values instead of container of pointers easier...