integrated runtime heatmap data into summary heatmap figure

[carns]

When DXT is not present, use the DXT heatmap module data to recreate figure.

• new logs repo example that includes heatmap module data (from an actual run)
• new logs repo example that has both heatmap and dxt data for sanity check
• bindings for heatmap module
• summary code to use heatmap data

[carns]

We can knock out the first two checkboxes on this with the same run. @shanedsnyder is looking into running an E3SM benchmark example on Cori for this purpose.

[shanedsnyder]

See darshan-hpc/darshan-logs#22 and darshan-hpc/darshan-logs#23 for example logs for this work. The former is a smaller scale example that could be used as a starting point that is easy to visually inspect, the latter is a pretty large-scale stress test once we're confident with the first.

[nawtrey]

With gh-615 merged I checked off the bindings.

[shanedsnyder]

Closed via #715