CellID changes

CellID field is now used to encode and access the detectorID of any given collection. For that an encoding for hit collections was introduced. Additionally clusters now access this field in a correct manner. The clusterID was totally removed from EUTelescope.
Still TODO: replace the setQuality() routine from clusters. This is not the place to do it!
Addressing issues: #27, #25, #11, #38. Issue #27, #38 can be closed after merge.