Multiple bugs in TQUniqueCut

The somewhat rarely used class TQUniqueCut has a couple issues, largely originating from pre-xAOD times:

• the required branch names are not correctly propagated. Instead of asking the run/event no. Observables their expressions are simply returned (i.e. their "branch names").
• the run and event numbers are stored as int, while at least the event numbers can easily exceed the 32 bit range -> needs to be long
• Currently, asking TQCut to create a clone of a cut hierarchy does not correctly clone TQUniqueCuts but instead creates instances of TQCut in their place

related to #256 (closed)