Behave according to the new rule from XEP-0045, section 7.2.2:
> When a MUC service receives an <x/> tagged join stanza from an
> already-joined client (as identified by the client's full JID),
> the service should assume that the client lost its synchronization,
> and therefore it SHOULD send exactly the same stanzas to the client
> as if it actually just joined the MUC.
When a user has several resources joined to a room using the same
nick attempts to leave the room from a single resource, route
presence-unavailable back to this (and only this) resource.
Fixes#2007
When a presence-error is received from a participant in a MUC, kick
only this particular participant's full JID, leaving other resources
untouched. This will prevent from erroneous kicking all user's resources
in the presence of "multi-session nicks".
The changes are very similar to those from previous commit:
* Now there is no need to pass validating function in
gen_mod:get_opt() and gen_mod:get_module_opt() functions,
because the modules' configuration keeps already validated values.
* New functions gen_mod:get_opt/2 and gen_mod:get_module_opt/3 are
introduced.
* Functions gen_mod:get_opt/4 and get_module_opt/5 are deprecated.
If the functions are still called, the "function" argument is
simply ignored.
* Validating callback Mod:listen_opt_type/1 is introduced to validate
listening options at startup.
It's now possible to use files as internal packet queues.
The following options are introduced:
* queue_type: the option can be set to `ram` (default) or `file`.
The option can be set per virtual host.
* queue_dir: path to the directory where queues will be allocated.
The default is 'queue' directory inside Mnesia directory.
This is a global option and cannot be set per virtual host.
Now 'From' and 'To' arguments must be omitted in functions
and structures related to routing.
The commit deprecates the following functions:
ejabberd_router:route/3 in favor of ejabberd_router:route/1
ejabberd_router:route_error/4 in favor of ejabberd_router:route_error/2
ejabberd_local:route_iq/4 in favor of ejabberd_local:route_iq/2
ejabberd_local:route_iq/5 in favor of ejabberd_local:route_iq/3
The format of {route, From, To, Packet} is changed in favor of {route, Packet}
