Removed different treatment of cluster size calculations for EtaCorrecti...

...on method.

The cluster size has no relation to the centroid method and should be calculated in the same way for all.

If using filter_cluster=True the results before and after this change are the same, as only matched clusters remain.
However, with filter_cluster=False the old code will count every cluster (even non-matched) for the EtaCorrection method.
I think this is the wrong way to do it.

Also:
Tidy and new control plot for FindMatchedCluster.

In EudetData.py:
- tidied FindMatchedCluster
- added catch incase of no clusters
- fill control plot of track-cluster distance (helps determine r_max)

In pyEudetReconstructionOnly.py:
- create control plot, pass to FindMatchedCluster and save at the end