For changing SpecA's central momentum type

mezzo@control:
mezzo > setCentMomA <momentum>

where <momentum> is in MeV. Algorithm takes some time, but after 20 min the rough magnet fields are right and measurements can be taken. At this beamtime the NMR is out of order so the fine adjustment is not working. This is why the routine can be aborted after about 45 min.