Updates to THcShower, THcShowerArray and THcSHowerHit

THcShowerHit.h and THcShowerHit.cxx
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1) Added fY for horizontal position
2) Added fY to THcShowerHit

THcShower.h
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1) Added variables
2) Added method addY, clY to get the cluster Y position

THcShower.cxx
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1) Added variables to the tree for "layer" detector
    either SHMS preshower or HMS layers
2) Added variables if the SHMS "array" is used
3) Added y position to THcShowerHit in CoarseProcess
4) In FineProcess, if SHMS "array" used then fill X,Y info
     for the Cluster and the "best" track that matched the cluster

THcShowerArray.h and THcShowerArray.cxx
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1) Added methods to Get the array cluster size, X and Y position
   and block number that has the highest energy in the cluster
2) Added array fBlockClusterID for all blocks. initialized to -1
   for each block for each event and then filled with
   the cluster number if the block is included in the cluster
3) Add variable fNhits and fNgoodhits