Basic anyhow integration

[repi]

This adds an optional integration for the anyhow error crate that can be enabled with the with_anyhow feature.

It works very similar to the failure crate but does not here support backtraces, as anyhow only supports backtraces on nightly. One could implement support for nightly-only backtraces but we don't have a need for that so didn't do it in this PR.

Fix #162

[repi]

Any feedback on the change? Something you would be able to integrate?

[quininer]

I understand that sentry has recently changed in open source, is sentry no longer accepting community contributions?

[repi]

@quininer only the licensing for the server components changed: https://twitter.com/mitsuhiko/status/1192188542988038146. and sentry-rust is a client-side only library

[siedentop]

@repi could you please update the branch with the base branch?

[siedentop]

This looks good to me. And I have been successfully using this.

However, my Rust knowledge is not good enough to review the code.

Also, it would be great to have some tests here. Would you mind taking a look at this?

[repi]

The maintainers of this repo have not given any feedback about this in 3 months, I will not do any further work on this. We have our own fork of sentry-rust that we use for now with this and additional changes.

[Tomcc]

As of a few hours ago failure has been deprecated, so this issue probably became a lot more important.
sentry is the only crate preventing me from switching from failure to anyhow... I could always write my own integration, but it'd be nice to give this PR some more love instead :)

[Swatinem]

I’m making good progress with the internals, and will try to get to all the open PRs in the next few weeks :-)

[Swatinem]

closing, as this was added in #212