ENH: Set block assignment in PV GenericIO reader

This commit adds capability to allow the user to select the
block assignment strategy in the GenericIO reader wrapped
in ParaView.
ENH: Set block assignment in PV GenericIO reader

This commit adds capability to allow the user to select the
block assignment strategy in the GenericIO reader wrapped
in ParaView.

From: George Zagaris <george.zagaris@kitware.com>

git-svn-id: https://svn.alcf.anl.gov/repos/DarkUniverse/hacc/trunk/cosmotools@1526 952bdfbe-fa2e-45c0-a9ae-ac90d4a62daf
Merge branch 'svn/trunk'