[ticket/13126] Improve the feedback when running the migrations

PHPBB3-13126
[ticket/13126] Extends migrator_output_handler instead of using a closure

PHPBB3-13126
[ticket/13126] Move migrator_output_handler to an interface

PHPBB3-13126
[ticket/13126] Change messages verbosity levels

PHPBB3-13126
[ticket/13126] Fix tests

PHPBB3-13126
[ticket/13193] Add link to post count in PMs

PHPBB3-13193
[ticket/13193] Add load_search config check

PHPBB3-13193
[ticket/13193] Make template more readable

PHPBB3-13193
[ticket/13126] Add missing use statement

PHPBB3-13126
Merge remote-tracking branch 'Nicofuma/ticket/13126' into ticket/13211
[ticket/13211] Add log wrapper for writing database updater to log file

PHPBB3-13211
[ticket/13211] Move console migrator output handler to db folder

PHPBB3-13211
[ticket/13211] Also use log wrapper output handler for console migrations

PHPBB3-13211
[ticket/13211] Move console migrator output handler back to console folder

PHPBB3-13211
Merge pull request #3060 from marc1706/ticket/13211

[ticket/13211] Add log wrapper for writing database updater to log file
Merge commit '078e0c1e440f7f906b670348e8da00141e245876' into prep-release-3.1.0

* commit '078e0c1e440f7f906b670348e8da00141e245876':
  [ticket/13211] Move console migrator output handler back to console folder
  [ticket/13211] Also use log wrapper output handler for console migrations
  [ticket/13211] Move console migrator output handler to db folder
  [ticket/13211] Add log wrapper for writing database updater to log file
  [ticket/13126] Add missing use statement
  [ticket/13126] Fix tests
  [ticket/13126] Change messages verbosity levels
  [ticket/13126] Move migrator_output_handler to an interface
  [ticket/13126] Extends migrator_output_handler instead of using a closure
  [ticket/13126] Improve the feedback when running the migrations
Merge branch 'prep-release-3.1.0' into develop-ascraeus

* prep-release-3.1.0:
[ticket/13215] Update Symfony components to v2.3.21.

PHPBB3-13215
Merge pull request #3062 from bantu/ticket/13215

[ticket/13215] Update Symfony components to v2.3.21.
Merge branch 'prep-release-3.1.0' into develop-ascraeus

* prep-release-3.1.0:
  [ticket/13215] Update Symfony components to v2.3.21.