We should use socks5h instead of socks5 when possible

Socks5-hostname does DNS over the proxy then connects via the proxy, whereas Socks5 does DNS using the system resolver, then connects to the received I.P. via the Socks5 proxy.

This hasn't caused problems so far, but while testing the 7.0 alpha, at least curl refuses to lookup the .onion TLD (which is a regression compared to 6.19). curl can be trivially fixed via putting an 'h' in ALL_PROXY.

To Do

• list all cases where we hardcode a socks5 proxy
• curl