Version 0.1 (Initial version)
Version 0.2:
- Fixed bugs related to turning MPI compilation off.
- Added more text to README to improve understanding.
- Added new Makfile.x86linux.gcc for non-opteron systems.
- Made MPI_Wtime the default timer when in MPI mode.
Version 0.3:
- Fixed a performance bug in make_local_matrix.cpp that was 
  very noticeable when the fraction of off-processor grid 
  points was large.
Version 0.4:
- Made total_nnz a "long long" so that MFLOP numbers were valid
  when the nonzero count is  more than 2^31.
Version 0.5:
- Added timing for Allreduce calls in MPI mode, printing min/max/avg times.
- Set the solver tolerance to zero to make all solves take max_iter iterations.
- Changed accumulator to a local variable for ddot.  It seems to help dual-core
  performance.
