Extracting common GenericIO functionality/utils

This commit extracts common GenericIO routines from the GenericIO
reader s.t. they can be leveraged in the development of the
streaming reader.

Conflicts:
	ParaViewCore/VTKExtensions/CosmoTools/vtkPGenericIOReader.cxx
	ParaViewCore/VTKExtensions/CosmoTools/vtkPGenericIOReader.h

Change-Id: Icaa3eb7caddcd677b4ab2bb9dea3888037511020
WIP: Streaming GenericIO reader

Change-Id: Ice9570ca2252a52ae91350e7f0bfe2f5e1240e4f