[ticket/11942] Delete post/topic reason should be added to logs

https://tracker.phpbb.com/browse/PHPBB3-11942

PHPBB3-11942
[ticket/11942] Adding the reason to hard deleted topic/post

PHPBB3-11942
[ticket/11942] Change the formulation

PHPBB3-11942
[ticket/11942] Edits messages

PHPBB3-11942
[ticket/11942] Always display delete reason

PHPBB3-11942
[ticket/11942] Apply the modifications to subsilver

PHPBB3-11942
[ticket/11942] Remove useless IF in templates

PHPBB3-11942
[ticket/11942] Don't show the checkbox if the post is already soft-deleted

PHPBB3-11942
[ticket/11942] Don't change the reason to '' when hard deleting

PHPBB3-11942
Merge pull request #2357 from Nicofuma/ticket/11942

[ticket/11942] Delete post/topic reason should be added to logs

* Nicofuma/ticket/11942:
  [ticket/11942] Don't change the reason to '' when hard deleting
  [ticket/11942] Don't show the checkbox if the post is already soft-deleted
  [ticket/11942] Remove useless IF in templates
  [ticket/11942] Apply the modifications to subsilver
  [ticket/11942] Always display delete reason
  [ticket/11942] Edits messages
  [ticket/11942] Change the formulation
  [ticket/11942] Adding the reason to hard deleted topic/post
  [ticket/11942] Delete post/topic reason should be added to logs