MPI implementation of 2-D grid solver.

Files:

	grid.{c,h}:       Core code for solver
	heat.c:           Main function
	cycletimer.{c,h}: Timing code

Compilation options:
	heat:        Standard MPI version.  Uses asynchronous sends and synchronous receives
	heat-asynch  MPI version that uses asynchronous sends and receives.

	Run ./heat -h for list of command-line options.