Support Accept and Accept-Encoding

[sfackler]

[DusterTheFirst]

Is there any reason for this not moving forward?

[coriolinus]

At a guess, it's because the Accept specification is complicated, and it's not a super high priority for Hyperium team members right now.

I'm working on an implementation right now, but no idea what the response would be to a PR upstreaming it.

[coriolinus]

https://github.com/coriolinus/accept-header

[maxcountryman]

After surveying the crate ecosystem, I found that third party Header implementations either:

1. Depended on the "rotting" mime crate or
2. Deviate from the spec.

And in some cases both.

Also the linked crate above is not available via crates.io.

So I published headers-accept which addresses these issues: it uses the mediatype crate instead of mime and adheres to spec without e.g. sorting when not called for by the spec. It also incorporates the spec-compliant parsing technique used by mediatype.