[ticket/12492] Add support of special chars

Add support of special chars during db test in the installation

PHPBB3-12492
[ticket/12864] Add template event to header after stylesheets

https://tracker.phpbb.com/browse/PHPBB3-12864

PHPBB3-12864
[ticket/12882] Update search_type when it's not prefixed by phpbb_search

PHPBB3-12882
[ticket/12882] Use a new migration

PHPBB3-12882
[ticket/12864] Update event docs

PHPBB3-12864
Merge pull request #2425 from Zoddo/ticket/12492

[ticket/12492] Add support of special chars

* Zoddo/ticket/12492:
  [ticket/12492] Add support of special chars
Merge branch 'develop-olympus' into develop-ascraeus

* develop-olympus:
  [ticket/12492] Add support of special chars
Merge pull request #2767 from Nicofuma/ticket/12882

[ticket/12882] Update search_type when it's not prefixed by phpbb_search

* Nicofuma/ticket/12882:
  [ticket/12882] Use a new migration
  [ticket/12882] Update search_type when it's not prefixed by phpbb_search
Merge remote-tracking branch 'VSE/ticket/12864' into develop-ascraeus