[ticket/11342] Mark active topics read when marking forums read

Marking forums read while viewing a category will also mark the active
topics inside that category read. Therefore, the active topics should also
be marked read. With this patch the ajax callback "mark_forums_read" will
check if the active topics id ("active_topics") exists and also mark
topics read if it does. As the active topics will only be displayed in
categories, which can't have any other topics, this is a proper approach.

PHPBB3-11342
[ticket/10896] Adds email validation to email settings in ACP

Adds a new validation type to the ACP validate_config_vars function
and implements it on the board_contact and board_email settings.

PHPBB3-10896
[ticket/10896] Move EMAIL_INVALID_EMAIL to common, replace EMAIL_INVALID

PHPBB3-10896
[ticket/11342] Fix "unexpected token" syntax error

PHPBB-11342
[ticket/11361] Make sure that array passed to strtr() has the proper format.

The array $date_cache[$format]['lang'] passed to strtr() contains a sub-array
which results in an E_NOTICE being thrown for 'Array to string conversion' on
PHP 5.4.
Ensure that the array passed to strtr() is one-dimensional by filtering out
non-string values.

PHPBB3-11361
[ticket/11298] Fix typo in language key; EXTENSIONS -> EXTENSION

PHPBB3-11298
[ticket/11122] Add EXreaction to docs/AUTHORS.

PHPBB3-11122
[ticket/11122] Move rxu to 'Former Contributors' section.

PHPBB3-11122
[ticket/7262] Backport set_config() and set_config_count() docs from develop.

PHPBB3-7262
[ticket/7262] Add $is_dynamic example to set_config() and set_config_count().

The logic is the other way around here in comparison to develop's
phpbb_config_db class, so add examples to make things more clear.

PHPBB3-7262
[ticket/7262] Add note about set_config() not updating is_dynamic.

PHPBB3-7262
Merge remote-tracking branch 'imkingdavid/ticket/11298' into develop

* imkingdavid/ticket/11298:
  [ticket/11298] Fix typo in language key; EXTENSIONS -> EXTENSION
Merge remote-tracking branch 'github-bantu/ticket/7262' into develop-olympus

* github-bantu/ticket/7262:
  [ticket/7262] Add note about set_config() not updating is_dynamic.
  [ticket/7262] Add $is_dynamic example to set_config() and set_config_count().
  [ticket/7262] Backport set_config() and set_config_count() docs from develop.
Merge branch 'develop-olympus' into develop

* develop-olympus:
  [ticket/7262] Add note about set_config() not updating is_dynamic.
  [ticket/7262] Add $is_dynamic example to set_config() and set_config_count().
  [ticket/7262] Backport set_config() and set_config_count() docs from develop.

Conflicts:
	phpBB/includes/functions.php
Merge remote-tracking branch 'github-bantu/ticket/11122' into develop-olympus

* github-bantu/ticket/11122:
  [ticket/11122] Move rxu to 'Former Contributors' section.
  [ticket/11122] Add EXreaction to docs/AUTHORS.
Merge branch 'develop-olympus' into develop

* develop-olympus:
  [ticket/11122] Move rxu to 'Former Contributors' section.
  [ticket/11122] Add EXreaction to docs/AUTHORS.
Merge remote-tracking branch 'github-exreaction/ticket/10896' into develop-olympus

* github-exreaction/ticket/10896:
  [ticket/10896] Move EMAIL_INVALID_EMAIL to common, replace EMAIL_INVALID
  [ticket/10896] Adds email validation to email settings in ACP
Merge branch 'develop-olympus' into develop

* develop-olympus:
  [ticket/10896] Move EMAIL_INVALID_EMAIL to common, replace EMAIL_INVALID
  [ticket/10896] Adds email validation to email settings in ACP

Conflicts:
	phpBB/adm/index.php
	phpBB/language/en/common.php
	phpBB/language/en/ucp.php
[ticket/10896] Add missing email validation lost in develop merge

Fix incomplete merge, by adding a piece of code moved to another file in
olympus back.

PHPBB3-10896
Merge remote-tracking branch 'github-bantu/ticket/11361' into develop-olympus

* github-bantu/ticket/11361:
  [ticket/11361] Make sure that array passed to strtr() has the proper format.