Prepare framework for new MUST detector subsystem
Remove ECbmModuleId::kEcal from the enumerator and reuse the connected integer value 7 for the new entry ECbmModuleId::kMust. Remove all usage of ECbmModuleId::kEcal from the source code and implement the usage of ECbmModuleId::kMust at the required places. In CbmMCTrack the information of the MUCH and MUST part of the muon system is added to the the same counter. Prepare the geometry interface classes for the new code but currently comment it since the detector code is missing since it will be only added with a later commit.