Support Reqwest as an underlying client

[blind-oracle]

Current hyper-tls dependency brings OpenSSL which sucks when cross-compiling e.g. to MUSL static.
Making it depend on rustls instead would be nice somehow.

Ideally maybe we can have some generic trait like the sealed HttpClient but public and with generic Request/Response from an http crate and Body from http_body.

I can try to make a PR if that approach is acceptable.

[cole-h]

#102 will at least make it possible to use rustls instead of openssl.

[blind-oracle]

@cole-h Yeah I did that in my fork already before I saw the others :) But I guess reqwest is more mainstream since hyper is kind of hiding its clients in 1.0 release...

[loyd]

I have a branch with hyper-v1 and rustls, but not enough tested yet. And because of #102 I need some time to figure out how I should merge these all together (or just close that PR, sorry)

[loyd]

hyper v1 is merged in the master branch. Now, either @cole-h or I should rebase #102 (it's still easy with hyper_util::client::legacy) to finally bring rustls and release a new version.

[loyd]

Note also, I'm not going to support the reqwest crate for now, because it's too high-level and can complicate future optimizations. Moreover, I want to have tcp+Native mode in the future.

So, I'm closing this issue.