[ticket/12690] Add core.submit_pm_after event

Add core.submit_pm_after to funtion submit_pm.
Event will return just submited msg_id. It should be plased
just before return $data['msg_id'];

Justification:
Using only core.submit_pm_before does not allow to
follow up after message submission.
The message ID is recieved at DB submission.
Some times we need the MSG_ID as identifier

PHPBB3-12690
[ticket/12690] Add other info to core.submit_pm_after

Added $mode
Added $subject
Added $data
Added $pm_data

PHPBB3-12690
[ticket/12690] Remove $msg_id and chmod

Remove inneded $msg_id
Chmod file to 644

PHPBB3-12690
[ticket/12690] Find a space

Lost a spce there ... found it ...

PHPBB3-12690
Merge pull request #2574 from lucifer4o/ticket/12690

[ticket/12690] Add core.submit_pm_after event

* lucifer4o/ticket/12690:
  [ticket/12690] Find a space
  [ticket/12690] Remove $msg_id and chmod
  [ticket/12690] Add other info to core.submit_pm_after
  [ticket/12690] Add core.submit_pm_after event