IPv6: initial preparing patches

(A) Added a sock_t typedef for clarity reasons.
(B) Added address family and port to Networking_Core.
(C) network.*::sendpacket(): signature change, as the family stored in Networking_Core will be required for IPv6
(D) Added structures for IPv6
(E) Copied and expanded resolve_addr() as addr_resolve_or_parse_ip().
(F) Added ipany_ntoa() to convert an IPAny into a printable string.
(G) Fixed formatting.
(H) Added ipport_equal().
(I) Fixed with the help of autobuild.