remove rechit merger module from clustering (working on better alternative for full HGC clustering)
release memory used by rechit hashmap
add missing header
checkpoint before merging memfix
Merged hgc_memfix from repository lgray

Conflicts:
	RecoParticleFlow/PFClusterProducer/python/particleFlowClusterHGCEE_cfi.py
	RecoParticleFlow/PFClusterProducer/python/particleFlowRecHitHGC_cff.py
	RecoParticleFlow/PFClusterProducer/test/run_display.sh
unified hgc hit navigator