[ticket/12608] Improve notifications drop-down menu styling in header

PHPBB3-12608
[ticket/12608] Updated tests

PHPBB3-12608
[ticket/12608] Add styling (CSS class) options to notifications

This will allow different notifications to have different styles

PHPBB3-12608
[ticket/12608] Clean up whitespace

PHPBB3-12608
[ticket/12608] Improved LTR and various bugfixes

PHPBB3-12608
[ticket/12608] Remove somewhat redundant reported color style

PHPBB3-12608
[ticket/12608] Changed get_styling() to get_style_class()

PHPBB3-12608
[ticket/12608] Add subSilver

PHPBB3-12608
[ticket/12608] Change CSS classes to prevent styling conflicts

PHPBB3-12608
[ticket/12726] PSR2.Namespaces.NamespaceDeclaration

PHPBB3-12726
[ticket/12726] Ensure PHP files do not contain any unused use statements

PHPBB3-12726
[ticket/12726] Fix coding style

PHPBB3-12726
[ticket/12726] Update error message

PHPBB3-12726
[ticket/12726] Fix coding style

PHPBB3-12726
Merge remote-tracking branch 'PayBas/ticket/12608' into develop-ascraeus

* PayBas/ticket/12608:
  [ticket/12608] Change CSS classes to prevent styling conflicts
  [ticket/12608] Add subSilver
  [ticket/12608] Changed get_styling() to get_style_class()
  [ticket/12608] Remove somewhat redundant reported color style
  [ticket/12608] Improved LTR and various bugfixes
  [ticket/12608] Clean up whitespace
  [ticket/12608] Add styling (CSS class) options to notifications
  [ticket/12608] Updated tests
  [ticket/12608] Improve notifications drop-down menu styling in header
Merge pull request #2625 from Nicofuma/ticket/12726

[ticket/12726] Add Code Sniffer sniff ensuring PHP files do not contain any unused use statements

* Nicofuma/ticket/12726:
  [ticket/12726] Fix coding style
  [ticket/12726] Update error message
  [ticket/12726] Fix coding style
  [ticket/12726] Ensure PHP files do not contain any unused use statements
  [ticket/12726] PSR2.Namespaces.NamespaceDeclaration