Test plots for Mira communications measurements

Ran mmli on Mira with no code optimization and measured communication
time and variability on up to 128 cores. Also compared 128 cores on 128
nodes (using 1 core per node) versus 128 cores on 8 nodes (using 16
cores per node). Experiments with non-default torus mapping passed as
an environment variable did not work except for default ABCDET.