ApplyCal should not load all (H5) solutions in memory
When using a H5Parm file, ApplyCal will grid all solutions (all timesteps, channels, antennas) in memory. For a standard LOFAR obs, this comes down to 1.5 GB per step, times the nr of corrections. When using H5ParmPredict, this 1.5 GB x a few is multiplied another 50 times, causing a run on a 192 GB machine to fail.