Switch all engine tests to NUnitLite

[CharliePoole]

Since the console depends on the engine, having it's tests run by the engine creates a (kind of) circularity. It's cleaner if the tests don't depend on anything but the engine.

The console tests are currently run by the console we just built. I'm willing to keep doing that until / unless it poses a problem.

This issue is being written to replace #780

[CharliePoole]

I switched the net20 engine tests to nunitlite and found that the test run hung after that test appeared to complete. The call to StartProject in the cake script never returns.

Cake has had past issues like this and this may be a regression. It only appears to happen when I'm calling the net35 tests of the net20 engine. I'll try to work it out with the Cake project after the release.

[CharliePoole]

After spending more time on this, I figured out that it's not a Cake problem but is caused by one of our own tests. The test didn't properly dispose of a runner acquired from the engine so the process couldn't terminate.

[CharliePoole]

This issue has been resolved in version 3.15.0-beta1

The release is available on:
GitHub.
NuGet packages are also available NuGet.org and
Chocolatey Packages may be found at Chocolatey.org