Run tests asynchronously

[Leandros]

This is a big one, I know, but with increasing number of tests I found catch to become very slow.
Since the tests in each TEST_CASE are (or rather should) be self-contained, it would be great if there was a knob to turn which runs all tests in parallel (up to N, where N is usually number of cores).

This would require a couple of changes I presume, since not even REQUIRE on it's own is thread-safe.

[Leandros]

I've seen this has been requested in the past, and is mentioned in the known limitations. I'd still like to nag you. The current solutions are not satisfying.

[horenmar]

Not happening.

To expand on it a bit, we have decided that having parallel runner is out of scope for Catch, and getting multiple tests to run in parallel should instead be left for external test runners.

We do however plan to have (optionally?) thread-safe assertions at some point.

[JoeyGrajciar]

Closing based on last comment