[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/12268] Extension finder should not crawl through .git/ of extensions

This new filter ignores .svn and .git directories.
When searching for php classes and template files of extensions
we don't need to look inside these directories.

PHPBB3-12268
[ticket/12268] Use FilesystemIterator::SKIP_DOTS

PHPBB3-12268
[ticket/12268] Do not search in folders starting with a dot

PHPBB3-12268
[ticket/12268] Move class out of extension namespace and rename it

PHPBB3-12268
[ticket/12268] Rename class file to recursive_dot_prefix_filter_iterator.php

PHPBB3-12268
[ticket/12268] Do not use substr but just compare the character

PHPBB3-12268
[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/12035] Adding link to user posts to ACP page

Adding link of posts behind displayed number of posts of the user

PHPBB3-12035
[ticket/11904] Update explanation for what Allow CDN does

PHPBB3-11904
[ticket/12278] Add mcp.php core event to allow to modify modules display option

This event allows extensions to set display option for custom MCP modules
for extensions which add custom MCP modules
and some of them should be displayed conditionally.

PHPBB3-12278
[ticket/8309] Removing key with similar function to avoid redundancy

PHPBB3-8309
[ticket/12284] Improve readability of extension manager details

Use span tags like the rest of the ACP does, instead of P tags.
There is no semantic need to use P tags here. These are not
paragraphs.

PHPBB3-12284