mod_admin_shell: Add session.is_connected() method

mod_admin_shell: Add session.write() method to write data to client with no \n

util.prosodyctl.shell: Support for receiving partial lines (no automatic \n)

util.logger: Return sink_function from add_simple_sink() This allows a simple sink to be later removed via remove_sink()

util.logger: Support for removing individual log sinks without a full reset

mod_admin_socket: Comment on LuaSocket UNIX compat code Ref #1717

mod_admin_socket: Compat for luasocket prior to unix datagram support The "socket.unix" module exported only a function before https://github.com/lunarmodules/luasocket/commit/aa1b8cc9bc35e56de15eeb153c899e4c51de82a8 when datagram support was added. Fixes #1717 Thanks rsc and lucas for reporting and testing

mod_invites_register: Push invitee contact entry to inviter Invitee would not show up in the roster of the invite creator unless they fetch their roster afterwards. Fixes #1715 Thanks gerald

prosodyctl: check turn: warn about external port mismatches behind NAT Some NATs don't preserve port numbers, which can cause the TURN server's reported relay address to be incorrect (the TURN server has no way to predict what the external port is, so it can't be corrected in config like an IP mismatch can).

Added tag 0.12.0 for changeset 50fcd3879482