Show result differences between runs

[joanhey]

After every run, the most important question is know the difference in results.

Now we only have the results, and we need to check vs the last run and perhaps also to the last round.
That take a lot of time for checking.

Please could you include the differences between runs (and perhaps also to the last round) like you have in:
https://www.techempower.com/benchmarks/previews/round14/r14p1.1-vs-r14p2.html

Thank you

[bhauer]

We have this partially complete. I'll review the status when I get a moment and see if we can push this out soon.