Rewrite and Improvements for PFRecHit and PFCluster Producers

Built on top of CMSSW_7_1_0_pre3.
This PR is a complete rewrite of PFRecHit and PFCluster Producers/Algos.

Expected changes:
- Timing improvements to PFRecHit and PFCluster producers across the board 
   - Some large, esp. preshower rechits
- Changes per-cluster in energy and position assignment in some small cases where we have corrected the navigation topology. ECAL and HCAL are affected here.
   - Previously it was sometimes the case that a was a neighbor of b and b was not of a in ecal endcap.
   - We no longer use the CaloTower det ID navigation, this causes some churn in the HCAL clusters.
- Churn in Jet and MET responses per-event due to cluster changes, but no change in the resulting distribution Mean/RMS/Tails.