Accept-Encoding support

[Jille]

Hi. Thanks for the library :)

Any plans for adding Accept-Encoding support? It currently doesn't work, I suspect because "gzip, br" doesn't contain slashes like mime-types.

[aohorodnyk]

@Jille Thank you for the ticket. Could you please describe the whole use case for that and I'll be happy to add it.

[Jille]

I want to know which encodings are supported by the client. A browser might send Accept-Encoding: gzip, br, older browsers would not include br and a more minimal implementation might not send any header at all.

Based on this I'd let the server pick the best available compression.