If a pending stream management session times out, call
ejabberd_c2s:process_terminated/2 *before* storing the incoming stanza
count. Without this change, the session table entry that holds the
stanza count was purged while closing the session.
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.