* EXreaction/ticket/11259:
[ticket/11259] htmlspecialchars($phpbb_admin_path)
[ticket/11259] adm_relative_path -> phpbb_adm_relative_path
[ticket/11259] Also make adm_relative_path available in the container
[ticket/11259] Make phpbb_admin_path available everywhere
Conflicts:
phpBB/install/index.php
phpBB/install/install_update.php
PHPBB3-11015
This allows us to just create the object without having to include the
driver first. However, it also means that users must specify the full
class name in config.php