PV4FoamReaders: Updated to build with ParaView-5.0.0
paraFoam: Updated to load PV4FoamReaders for ParaView-5.0.0

Currently this is experimental but if it becomes clear that ParaView-4
and ParaView-5 are and will remain consistent with respect to readers
the plan is to rename

PV4 -> PV

or

PV4 -> PV45 if it is assumed that PV6 may need to be different.