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Muon code duplicated between LHCb and Rec

I noticed that several muon-related bits of code are now duplicated between LHCb and Rec, so far I haven't noticed any actual problems resulting from this, but some bits of the current master are, I think, very fragile.

The duplications I noticed are:

  • CommonMuonHit.h exists in both LHCb and Rec. At first glance these are identical, so the one in Rec can just be removed
  • CommonMuonStation.h exists in both LHCb and Rec. These are not identical (the constructor signatures differ), but they use the same macro as an include guard so will behave unexpectedly if both were included. We may have been saved from really weird behaviour because it looks like the data layout will be the same, even though other aspects of the definition differ.
  • MuonHitContainer.h in LHCb seems to be the modern version of MuonHitHandler.h in Rec. This isn't obviously such a problem, as here there is no name collision, but the Rec one could probably be removed.

Additionally, CommonMuonStation in LHCb (Muon/MuonDAQ) has a .cpp file that's only built as part of a module, not a library, so it cannot be linked against in other packages (I think this issue was hidden so far because users of this class linked against the copy in Rec (Muon/MuonID)).

Hopefully the duplication can just be removed, otherwise we should probably use some kind of namespace versioning to avoid using the same class names in different places with different definitions.

cc: @rvazquez @sstahl