[ticket/10325] trigger error if forgot password option disabled

PHPBB3-10325
[ticket/11495] Move tests to tree/ directory

PHPBB3-11495
[ticket/11495] Remove tests for add/remove we make them protected later

PHPBB3-11495
[ticket/11495] Remove fixing function from tree interface

The fixing function is implementation dependent.

PHPBB3-11495
[ticket/11495] Remove add/remove from the interface

PHPBB3-11495
[ticket/11495] Fix failing unit tests

PHPBB3-11495
[ticket/10325] add new config value to database

PHPBB3-10325
[ticket/10325] fix language

PHPBB3-10325
[ticket/10325] change language var

PHPBB3-10325
[ticket/10325] fix language variable

PHPBB3-10325
[ticket/10325] fix language key

PHPBB3-10325
[ticket/10325] improve acp option language

PHPBB3-10325
[ticket/10325] fix language in acp and ucp

PHPBB3-10325
[ticket/11237] Fix PHP error in acp_prune.php

Also making the code a bit more efficient (removing one SQL query)

PHPBB3-11237
[ticket/11495] Use constructor arguments over properties in implementation

PHPBB3-11495
[ticket/11236] Correct HTML

PHPBB3-11236
[ticket/11236] Do not require group selection in prune users

PHPBB3-11236
[ticket/11236] Change PRUNE_USERS_GROUP_EXPLAIN language

PHPBB3-11236
[ticket/10325] add logout function in functional_test_case

PHPBB3-10325
[ticket/10325] functional tests for forgot password functionality

PHPBB3-10325