MUC: Add support for advertising muc#roomconfig_allowinvites in room disco#info The de-facto interpretation of this (undocumented) option is to indicate to the client whether it is allowed to invite other users to the MUC. This is differs from the existing option in our config form, which only controls the behaviour of sending of invites in a members-only MUC (we always allow invites in open rooms). Conversations is one client known to use this disco#info item to determine whether it may send invites.