[ticket/12160] Add function to check if phpBB is installed.

PHPBB3-12160
[ticket/12160] Check if phpBB is installed before creating phpBB container.

PHPBB3-12160
[ticket/12160] Move phpbb_check_installation_exists() to functions_install.php

PHPBB3-12160
[ticket/12160] Use phpbb_check_installation_exists() in the other modules.

PHPBB3-12160
[ticket/8309] Renaming "Last visit" to "Last activity"

PHPBB3-8309
[ticket/8309] Rename $last_visit to $last_activity

PHPBB3-8309
[ticket/11169] Move module 'prune users' to users category

PHPBB3-11169
[ticket/8309] Moving key to get keys in alphabetical order

PHPBB3-8309
[ticket/10590] Remove confirmation page after posting

PHPBB3-10590
[ticket/11904] Update explanation for what Allow CDN does

PHPBB3-11904
[ticket/8309] Removing key with similar function to avoid redundancy

PHPBB3-8309
[ticket/10590] Fix functional tests are post confirm message removal

PHPBB3-10590
Merge remote-tracking branch 'prototech/ticket/12160' into develop

* prototech/ticket/12160:
  [ticket/12160] Use phpbb_check_installation_exists() in the other modules.
  [ticket/12160] Move phpbb_check_installation_exists() to functions_install.php
  [ticket/12160] Check if phpBB is installed before creating phpBB container.
  [ticket/12160] Add function to check if phpBB is installed.
[ticket/12198] Language issue in en/common.php

Deleted lines as they are not needed anymore.

PHPBB3-12198
Merge branch 'nickvergessen/ticket/elsensee/10590' into ticket/10590
[ticket/11357] Correcting invalid markup

PHPBB3-11357
[ticket/12285] Fix mult-lingual issues between extensions

PHPBB3-12285
[ticket/11766] Hide edit, quote and delete buttons if topic is locked

But show quote button to guests if topic isn't locked

PHPBB3-11766
Merge remote-tracking branch 'Elsensee/ticket/11766' into develop-olympus

* Elsensee/ticket/11766:
  [ticket/11766] Hide edit, quote and delete buttons if topic is locked
Merge branch 'develop-olympus' into develop

* develop-olympus:
  [ticket/11766] Hide edit, quote and delete buttons if topic is locked

Conflicts:
	phpBB/viewtopic.php