[ticket/12372] Unify definition of function dE() across all files

PHPBB3-12372
[ticket/12372] Move dE() function core.js

PHPBB3-12372
[ticket/12370] Add unit tests for topic notifications

PHPBB3-12370
[ticket/12372] Rename JS function dE() to phpbb.toggleDisplay()

PHPBB3-12372
[ticket/12361] Replace the Google logo.

Currently, a link to Google and its logo are displayed in the
language/en/help_bbcode.php file to explain how to correctly format tags
and to add an image to a post. However, the Google logo is outdated and
Google does not allow the use of its logo on third-party websites. Plus,
that overload their servers. I used the blue phpBB logo to replace it
because the grey one with transparent background is hardly visible.

Originally, I just refreshed the old Google logo with the new one
(https://www.google.com/images/srpr/logo5w.png) but Joas proposed to use
the phpBB logo, and I agree with him.

PHPBB3-12361
Merge branch 'ticket/mael/12361' into develop-ascraeus

* ticket/mael/12361:
  [ticket/12361] Replace the Google logo.
Merge remote-tracking branch 'Elsensee/ticket/12360' into develop-ascraeus

* Elsensee/ticket/12360:
  [ticket/12360] Fix duplicated creation of session when logging out the user
Merge remote-tracking branch 'paybas/ticket/12364' into develop-ascraeus

* paybas/ticket/12364:
  [ticket/12364] Add template identifier var to all missing pages
[ticket/11352] Add functional tests for disapproving a post/topic

PHPBB3-11352
Merge remote-tracking branch 'Marc/ticket/12362' into develop-ascraeus

* Marc/ticket/12362:
  [ticket/12362] Do not use database test case as it's not needed
  [ticket/12362] Add tests for schema generator
  [ticket/12362] Throw exception in schema generator on unresolvable dependency
[ticket/12369] White-space cleanup

PHPBB3-12369
Merge remote-tracking branch 'nickvergessen/ticket/12349' into develop-ascraeus

# By Joas Schilling
# Via Joas Schilling
* nickvergessen/ticket/12349:
  [ticket/12349] Fix Sniffer for @license tag
  [ticket/12349] Update license header in several new files
[ticket/12254] Persist set_lang after reg only if changed from default

PHPBB3-12254
[ticket/12363] Fix typo

PHPBB3-12363
Merge remote-tracking branch 'vsephpbb/ticket/12083' into develop-ascraeus

* vsephpbb/ticket/12083:
  [ticket/12083] Fix Select All in CODE bbcode with only one char
Merge remote-tracking branch 'paybas/ticket/12369' into develop-ascraeus

* paybas/ticket/12369:
  [ticket/12369] White-space cleanup
  [ticket/12369] Removed template vars initial state
  [ticket/12369] Added ACP vars
  [ticket/12369] Add template var {BODY_CLASS} to HTML body
[ticket/12373] Add to and from forum_id to LOG_MOVE log entries

PHPBB3-12373
[ticket/12283] Remove obsolete online class from posting review page

PHPBB3-12283
[ticket/12375] Fix broken attachment deletion.

The response is already parsed and when running it through parseJSON returned
null prior to 1.9. Now there's an actual error thrown, so the function is
returning and thus leaving the attachment row intact.

PHPBB3-12375
[ticket/10687] Improve error message if unable to get image dimensions

The error message that is presented if getimagesize() was unable to determine
an image's dimensions now additionally states that this might be caused by an
incorrect URL.

PHPBB3-10687