Korteweg de-Vries equation example

[NAThompson]

This should help with #2000.

A couple things:

• I should probably add a "step attribute" for the time.
• I will add graphing ability once the Python binding problems are hammered out.

[pnorbert]

Shouldn't we have this rather in https://github.com/ornladios/ADIOS2-Examples?

[NAThompson]

@pnorbert : That's fine; either way. But the fact that I had no clue that the ADIOS2-examples repo existed, along with the existence of an examples directory here, does not indicate that many other people will find it. It also appears less well-maintained, so I fear it will be susceptible to bitrot.

Finally, the Python code will act as a unit test for issue #2081.

[williamfgc]

@NAThompson I can help you migrating to the ADIOS2-Examples repo (in my spare time). Reality is, ADIOS2-Examples is easy to maintain as long as ADIOS2 doesn't break its API. As for unit tests, they should be under testing, there is nothing run/verified under examples so it got pretty outdated over time. Bonus: ADIOS2-Examples has CI on Azure.

[NAThompson]

@williamfgc : Ok, cool. I'll open a PR in the examples project.