net: add SetSocketNonBlocking() as OS independent wrapper
[Qt] small Qt-only include cleanup
Merge pull request #4586

f65352a [Qt] small Qt-only include cleanup (Philip Kaufmann)
Merge pull request #4491

eaedb59 net: add SetSocketNonBlocking() as OS independent wrapper (Philip Kaufmann)
extend core proxy options and handling

- rework the proxy handling in init to cover more cases and work more
  thoroughly
- add -proxy6 to allow setting a separate SOCKS5 proxy to reach peers via
  IPv6
- rework proxy data-structures to allow recognition of the default proxy
  (-proxy) to give users the ability to see, which proxy (IPv6 / Tor) is
  derived from the default proxy and which was explicitly set
- extend RPC call getnetwork info
- remove unneeded (int) casts before CLIENT_VERSION and PROTOCOL_VERSION
  in getinfo and getnetworkinfo RPC calls
remove nameproxy, as SOCKS5 proxies support name resolution
revert: add fIsDefault (squashme)