[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/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/11357] Correcting invalid markup

PHPBB3-11357
[ticket/12035] Adding necessary conditions

PHPBB3-12035
[ticket/12035] Correcting the condition

PHPBB3-12035
[ticket/12292] Improve style details page

http://tracker.phpbb.com/browse/PHPBB3-12292
Gave style details page a proper heading and back button.
Also removed a few obsolete code leftovers in the style
and CSS.

PHPBB3-12292
Merge remote-tracking branch 'vsephpbb/ticket/12292' into develop-ascraeus

* vsephpbb/ticket/12292:
  [ticket/12292] Improve style details page
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/12292] Improve style details page
Merge remote-tracking branch 'geetakshi/ticket/11357' into develop-ascraeus

* geetakshi/ticket/11357:
  [ticket/11357] Correcting invalid markup
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/11357] Correcting invalid markup
Merge remote-tracking branch 'vsephpbb/ticket/11904' into develop-ascraeus

* vsephpbb/ticket/11904:
  [ticket/11904] Update explanation for what Allow CDN does
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/11904] Update explanation for what Allow CDN does
Merge remote-tracking branch 'geetakshi/ticket/12035' into develop-olympus

* geetakshi/ticket/12035:
  [ticket/12035] Correcting the condition
  [ticket/12035] Adding necessary conditions
  [ticket/12035] Adding link to user posts to ACP page
Merge branch 'develop-olympus' into develop-ascraeus

* develop-olympus:
  [ticket/12035] Correcting the condition
  [ticket/12035] Adding necessary conditions
  [ticket/12035] Adding link to user posts to ACP page

Conflicts:
	phpBB/adm/style/acp_users_overview.html