Run 1/2 code cleanup in Rec master: Calo
cc @cattanem @rmatev @sstahl @graven
The Rec/Calo subdirectory is Run 1/2 code and can be removed when @cmarinbe and @jmarchan confirm that it no longer needed for developing CaloFuture.
Note that this does not apply to the Calo subdirectory in LHCb yet, e.g. LHCb/Calo/CaloKernel
is still needed (for how long?).