ENH: out-of-core support in cosmotools-driver

Implemented method for reading genericio particle datasets.
ENH: out-of-core support in cosmotools-driver

Implemented method for reading genericio particle datasets.

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

git-svn-id: https://svn.alcf.anl.gov/repos/DarkUniverse/hacc/trunk/cosmotools@1773 952bdfbe-fa2e-45c0-a9ae-ac90d4a62daf
Merge branch 'svn/trunk'