[ticket/12718] Use remove_topic_from_statistic() for delete_topic

PHPBB3-12718
[ticket/12718] Update docblock

PHPBB3-12718
[ticket/12710] Prepare get_existing_indexes() for other DBMS

PHPBB3-12710
[ticket/12710] Fix changing the column type on oracle

PHPBB3-12710
[ticket/12718] Fix docblocks

PHPBB3-12718
[ticket/12789] Remove the directories in \phpbb\cache\driver\memory::purge()

PHPBB3-12789
[ticket/12789] Move duplicated functions to the base class

PHPBB3-12789
[ticket/12937] Do not return false. Return null for get and array() for all.

PHPBB3-12937
[ticket/12738] Pass $this->config in content_visibility constructor

PHPBB3-12738
Merge pull request #2838 from dhruvgoel92/ticket/12738

[ticket/12738] Pass $this->config in content_visibility constructor

* dhruvgoel92/ticket/12738:
  [ticket/12738] Pass $this->config in content_visibility constructor
[ticket/12671] Possibility to use NOT LIKE expression

PHPBB3-12671
[ticket/12742] Add method for getting authenticated recipients

PHPBB3-12742
[ticket/12742] Add check for empty $users and add method to fitting methods

The method might now return an empty array in case of an empty users array,
too. The notification types then check if the returned array is empty and
return this if it is empty and if the notification types would otherwise
carry out other operations afterwards.

PHPBB3-12742
[ticket/12794] Properly validate google+ field against valid character set

PHPBB3-12794
[ticket/security-155] Cast the types of string values in the controller routes

SECURITY-155
Merge remote-tracking branch 'github-bantu/ticket/12937' into develop-ascraeus

* github-bantu/ticket/12937:
  [ticket/12937] Do not return false. Return null for get and array() for all.
[ticket/12671] Possibility to use NOT LIKE expression

PHPBB3-12671
[ticket/security-155] Fix spelling error in comment

SECURITY-155
Merge pull request #2841 from nickvergessen/ticket/security-155

[ticket/security-155] Cast the types of string values in the controller routes
[ticket/12710] Correctly fetch unique and normal indexes only in MSSQL

PHPBB3-12710