[ticket/11314] Cleanup core.js coding

function errorHandler() was used in returnHandler() before it was defined.
The unused variable alert has been removed from errorHandler(). Overuse of
the var keyword for the variable sign has been removed and the if
statement has been simplified. The definition of the variable i has been
moved outside of the for loop definition. The var keyword shouldn't be
used inside the definition of the for loop.

PHPBB3-11314
[ticket/11314] Add missing semi-colons

Omitting the semi-colon is not legal behavior for JavaScript.

PHPBB3-11314
[ticket/11314] Use return variable instead of overusing the return keyword

Use a return variable and modify it to our needs.

PHPBB3-11314
[ticket/11314] Add missing "use strict" to timezone.js files

PHPBB3-11314
[ticket/11314] Fix whitespace issues

PHPBB3-11314
[ticket/11314] Add missing radix parameters

PHPBB3-11314
Merge branch 'develop' of https://github.com/phpbb/phpbb3 into ticket/11314
[ticket/11362] Correctly sanitise the directory path

We need to correctly remove ../ form the path if possible by removing the
previous folder aswell. Otherwise the finder is unable to locate /adm/style
directories in extensions as he is looking for /adm/../adm/style instead.

PHPBB3-11362
[ticket/11362] Add unit test for ../ in directory paths

PHPBB3-11362
[ticket/11314] Fix issues mentioned in jshint report

Additionally, the editor.js files are now the same file in both
subsilver2, prosilver, and the acp.

PHPBB3-11314
[ticket/11314] Fix JSHint issues in adm editor.js

This time without changing the behavior.

PHPBB3-11314
[ticket/11314] Modify files to comply with coding standards

PHPBB3-11314
Merge branch 'develop' of https://github.com/phpbb/phpbb3 into ticket/11314

Conflicts:
	phpBB/styles/prosilver/template/timezone.js
[ticket/11485] add columns to styles table during updating schema before
updating the data

PHPBB3-10485
[ticket/11485] add revert_schema for the updated columns

PHPBB3-11485
[ticket/11225] Deletion of unused mcp_jumpbox.html file

The file/template is no longer used(as mentioned in it).

PHPBB3-11225
[ticket/11116] Made ACP "extension not available" error message E_USER_WARNING

The error message generated when an administrator tries to enable an
incompatible extension used to be displayed in the green of the default
E_USER_NOTICE. Changed it to E_USER_WARNING to make it appear in red, as
requested in the ticket.

PHPBB3-11116
[ticket/11492] Add functional test for empty teampage

PHPBB3-11492
[ticket/11492] Add tests for removing/adding users

PHPBB3-11492
[ticket/11492] Do not add the user again

PHPBB3-11492