[ticket/12841] Allow extensions to position new config vars

PHPBB3-12841
[ticket/12841] Fix white space issues reported by sniffer

PHPBB3-12841
[ticket/12841] Add a tests for the new function

PHPBB3-12841
[ticket/12841] prefix function name with phpbb_

PHPBB3-12841
[ticket/12841] Update comments in tests making after default

PHPBB3-12841
[ticket/12841] Make config position default to after

PHPBB3-12841
[ticket/12778] Automatically delete files on update

PHPBB3-12778
[ticket/12778] Rename the file to *.bak instead of deleting

PHPBB3-12778
[ticket/12886] Remove obsolete check for f_user_lock

The user shouldn't be able to unlock his own topic if he doesn't have m_lock
permissions. Also, the check for f_user_lock was never going to evaluate to
true due to the topic not being unlocked making it obsolete anyway.

PHPBB3-12886
[ticket/10404] Use anonymous function instead of create_function in acp/auth

PHPBB3-10404
[ticket/10404] Fix codesniffer complaint about anonymous function

PHPBB3-10404
Merge pull request #2815 from dhruvgoel92/ticket/12778

[ticket/12778] Automatically delete files on update

* dhruvgoel92/ticket/12778:
  [ticket/12778] Rename the file to *.bak instead of deleting
  [ticket/12778] Automatically delete files on update
Merge pull request #2832 from marc1706/ticket/10404

[ticket/10404] Use anonymous function instead of create_function in acp/auth

* marc1706/ticket/10404:
  [ticket/10404] Fix codesniffer complaint about anonymous function
  [ticket/10404] Use anonymous function instead of create_function in acp/auth
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
Merge pull request #2822 from marc1706/ticket/12886

[ticket/12886] Remove obsolete check for f_user_lock

* marc1706/ticket/12886:
  [ticket/12886] Remove obsolete check for f_user_lock
Merge pull request #2724 from VSEphpbb/ticket/12841

[ticket/12841] Allow extensions to position new config vars

* VSEphpbb/ticket/12841:
  [ticket/12841] Make config position default to after
  [ticket/12841] Update comments in tests making after default
  [ticket/12841] prefix function name with phpbb_
  [ticket/12841] Add a tests for the new function
  [ticket/12841] Fix white space issues reported by sniffer
  [ticket/12841] Allow extensions to position new config vars