Implement gzip content encoding

[clue]

Also refs reactphp/http-client#37

[clue]

This should be fairly easy to implement for the Promise-based API alone, but the streaming API would need a streaming zlib decoder, see also clue/reactphp-zlib#9.

[clue]

Note that this affected both Transfer-Encoding: gzip and Content-Encoding: gzip. The former can be used for transparent on-the-fly compression, while the latter is the one that is actually in use for most HTTP servers, see also https://stackoverflow.com/questions/11641923/transfer-encoding-gzip-vs-content-encoding-gzip and https://stackapps.com/questions/916/why-content-encoding-gzip-rather-than-transfer-encoding-gzip.

[irazasyed]

Any progress with this? Just hit a roadblock while working on a project.

[clue]

You can manually specify the required HTTP request headers and decompress the response body if the HTTP response indicates compression.

In the future, this should (will) be done automatically. As much as I'd like to commit to specific date, I can only say that we will get to this feature as soon as time permits.

(If you need this for a commercial project and/or you want to sponsor this feature, feel free to reach out and send me an email)

[clue]

I have to close this one as per #177 now that future development will focus on https://github.com/reactphp/http instead.

I've migrated this ticket to reactphp/http#377.