Modify the test utilities so that a test can be generated on one proc and run on n procs.

This test changes the way test data is compared. Instead of comparing line by line, it forms a key of the (t,x,y,z) coordinates and compares the values at those coordinates. Consequently, I also disable the check that the required number of procs are used. This allows us to have one set of test files, generated on a single proc, and run the test suite with multiple procs. This should make the disk space occupied by tests smaller, and make the existing tests more flexible.