[ticket/12459] Fix: the posts were always marked as unapproved

the database return a string, so the strict comparison always returned false

PHPBB3-12459
[ticket/12459] Fix: Soft deleted topics should appear in feeds

As for the posts, a soft deleted topic should appear (with a corresponding
message) in topic's based feeds.

PHPBB3-12459
[ticket/12459] Fix: Differentiating unapproved and deleted posts

Unapproved and deleted posts should not be displayed with the same message
(POST_UNAPPROVED)

PHPBB3-12459
[ticket/12459] Enable related tests

PHPBB3-12459
[ticket/12459] Change language strings

PHPBB3-12459
Merge pull request #2373 from Nicofuma/ticket/12459

[ticket/12459] Unapproved posts/topics are not correctly handled in feeds

* Nicofuma/ticket/12459:
  [ticket/12459] Change language strings
  [ticket/12459] Enable related tests
  [ticket/12459] Fix: Differentiating unapproved and deleted posts
  [ticket/12459] Fix: Soft deleted topics should appear in feeds
  [ticket/12459] Fix: the posts were always marked as unapproved