Document hpx_run_tests.py

[hkaiser]

The documentation needs to have a section describing how to run tests. This is probably best done in the getting started part, where we describe the installation process.

[brycelelbach]

I'm not sure I agree with this, as hpx_run_tests.py is an internal tool, not a user facing one (at least, it shouldn't be). You can add tests through CMake, and run them through the build system; you never need to touch hpx_run_tests.py

[hkaiser]

The point of this ticket is to get some developer documentation for times when you are MIA.

[brycelelbach]

Where should this documentation be placed?

[hkaiser]

What about adding some exhaustive comments in the file itself?

[brycelelbach]

There's already comments in the source code, explaining the input format. All the command line options are documented (--help). I'm not sure what else I should be documenting.