[ticket/11579] Move simple tests into seperate files

PHPBB3-11579
[ticket/11579] Rework calls to validate_data_helper

PHPBB3-11579
[ticket/11579] Add missing commas to validate_username_test

PHPBB3-11579
Merge branch 'develop' of https://github.com/phpbb/phpbb3 into ticket/11531
[ticket/11587] Pass legend and teampage settings to group_create()

Without passing those values, the group is removed from the teampage and
the legend while submitting the edit form on the ucp groups manage page.

PHPBB3-11587
Merge branch 'develop' of https://github.com/phpbb/phpbb3 into ticket/11587
[ticket/11587] Add functional tests for group teampage settings

The group_legend and group_teampage settings, which are needed for the
teampage, are tested with these newly added functional tests.
Duplicate code has been reduced as much as possible.

PHPBB3-11587
[ticket/10820] Inject IE version in function

PHPBB3-10820
Merge branch 'ticket/10820' into ticket/10820-develop

* ticket/10820:
  [ticket/10820] Inject IE version in function

Conflicts:
	phpBB/download/file.php
[ticket/10820] Change function call in tests

PHPBB3-10820
[ticket/10820] Fix copyright

PHPBB3-10820
[ticket/10820] Rename function

PHPBB3-10820
[ticket/10820] Add test cases
More test cases to check against different versions

PHPBB3-10820
[ticket/11579] Do not extend validate_data_helper

PHPBB3-11579
[ticket/11579] Add method for validating emails for valid MX and mark as slow

A method for setting up the prerequisities also has been added in order to
reduce the amount of necessary code.

PHPBB3-11579
[ticket/11481] Move feed factory to own file

PHPBB3-11481
[ticket/11481] Move feed base to own file

PHPBB3-11481
[ticket/11481] Move feed post base to own file

PHPBB3-11481
[ticket/11481] Move feed topic base to own file

PHPBB3-11481
[ticket/11481] Move overall feed to own file

PHPBB3-11481