TLS 1.3 support

[ioquatix]

Currently, it appears that only TLS 1.2 is working. It increases round-trip latency.

[ioquatix]

Incorrectly closed by unrelated commit.

[paddor]

What's the status here?

[ioquatix]

This was mostly a limitation of OpenSSL, and is now fully supported (by default), e.g.

https://www.cdn77.com/tls-test/result?domain=https://www.codeotaku.com