feat: Asynchronous experiment cancellation

[JoshHiles]

this closes #165

New experiment.WithCancellationToken() & overloads for the async Try & Catch

[JoshHiles]

Tests were failing on a21eb17 as the EnsureNullGuardIsWorking tests don't run in DEBUG mode, I'm wondering if we should remove this?

Anyways the null ref ex throws earlier as we build the Behaviours from the Candidate which causes the null ref ex to throw earlier. I think this is correct way to fix but open to feedback

[M-Zuber]

LGTM
there is that one variable that looks like it should have been removed

[JoshHiles]

there is that one variable that looks like it should have been removed

I've double checked the project build settings and we do have level 4 warnings & we don't have CS0168 excluded.
Just wondering if there's a way to catch this next time in VS?
Is this because we support net451 ?

[M-Zuber]

there is that one variable that looks like it should have been removed

I've double checked the project build settings and we do have level 4 warnings & we don't have CS0168 excluded. Just wondering if there's a way to catch this next time in VS? Is this because we support net451 ?

TBH I don't know
(and personally I am not that concerned about this particular error...)

[JoshHiles]

Groovy!
Apologies in advance, their will be another PR through for the release notes at somepoint