Updated the parser to calculate derived stats via various command line

options. The default option gives the same output as before.
  - File Counts
  - Performance (MiB/s)
  - Total Counts


git-svn-id: https://svn.mcs.anl.gov/repos/darshan/trunk@337 3b7491f3-a168-0410-bf4b-c445ed680a29