[ticket/10776] Fixed errors in docs/README.html.

PHPBB3-10776
[ticket/10776] Fixed a couple language changes in docs/README.html.

PHPBB3-10776
[ticket/10772] Use forum specific style for trigger_error

PHPBB3-10772
[ticket/10772] Functional tests for forum style

PHPBB3-10772
[ticket/10772] Remove unnecessary comment

PHPBB3-10772
[ticket/11145] Wrong error thrown when uploading a bigger image.

When attaching an image to a post with a size larger than maximum defined in
php.ini, 'ATTACHED_IMAGE_NOT_IMAGE' error is thrown. $file->is_image() is
returning false value when image size is too large. Therefore, moved
not image test down after image size test.

PHPBB3-11145
[ticket/11568] Use Goutte Client to install the board for functional tests

PHPBB3-11568
[ticket/11568] Set client manually so we can increase the cURL timeout

PHPBB3-11568
[ticket/11568] Any output before the doc type means there was an error

Change is needed to allow "Warning:" in the HTML body

PHPBB3-11568
[ticket/11568] Only use a static version of the client

PHPBB3-11568
[ticket/11568] Remove manual calls to assert_response_success()

PHPBB3-11568
[ticket/11568] Make CookieJar static aswell

PHPBB3-11568
[ticket/11568] Fix common_groups_test.php form handling

PHPBB3-11568
[ticket/11568] Trim the output to allow Tabs before INCLUDE overall_header

PHPBB3-11568
[ticket/11568] Allow different status codes

PHPBB3-11568
[ticket/11568] Add method to get page content

PHPBB3-11568
[ticket/11579] Add basic set of unit tests for validate_data()

This currently includes tests for the string, num, date, match, and
language iso validation functions.

PHPBB3-11579
[ticket/11568] Only assert string when doctype is there at all

PHPBB3-11568
[ticket/11568] Remove unused method

PHPBB3-11568
[ticket/11579] Add remaining unit tests for validate_data functions

This now includes tests for usernames, passwords, emails, and jabber
addresses. A few small changes had to be applied to phpbb_mock_cache
and phpbb_mock_user in order to incorporate needed methods.

PHPBB3-11579