[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
[ticket/11303] add S_TZ_PRESELECT template var

add a new template variable to check if timezone has already been selected
by the user while registeration.

PHPBB3-11303
[ticket/11303] use S_TZ_PRESELECT in subsilver

PHPBB3-11303
[ticket/11303] remove additional brackets

PHPBB3-11303
[ticket/11303] rename attribute to timezone-preselect

PHPBB3-11303
[ticket/11323] Correctly treat variables in template defines

Previously, any template variables that were used when defining a variable
were treated as strings. This is a regression to phpBB 3.0. With this
patch the template variables will be properly parsed.

PHPBB3-11323
[ticket/11323] Enable tests for inclusion of defined variables

PHPBB3-11323
[ticket/11323] Reduce additional code and revert regex to previous one

PHPBB3-11323
Merge branch 'develop' of https://github.com/phpbb/phpbb3 into ticket/11314
[ticket/11387] Log module added only after it has been added

PHPBB3-11387
[ticket/11383] Correctly revert modules added/removed by migrator

PHPBB3-11383
[ticket/11404] Return empty array of avatar data if $row is empty

While creating a group in the acp, the group data ($group_row) is empty.
Due to that array_combine in phpbb_avatar_manager::clean_row() will cause
PHP Warnings. In addition to that the required indexes 'avatar',
'avatar_width', 'avatar_height', and 'avatar_type' won't be defined. This
patch will solve that issue.

PHPBB3-11404
[ticket/11421] Correctly display submit button when needed

PHPBB3-11421
[ticket/11417] FIx submit button description on notifications options page

PHPBB3-11417
[ticket/11390] Hide pagination when there are no notifications

PHPBB3-11390