Merge remote-tracking branch 'Fyorl/ticket/10963' into develop

* Fyorl/ticket/10963:
  [ticket/10963] filespec::get_mimetype now used
  [ticket/10963] Removed superfluous ternary statement and strpos now stricter
  [ticket/10963] Modified filespec::is_image() to check actual mimetype
Merge PR #759 branch 'nickvergessen/ticket/10811' into develop

* nickvergessen/ticket/10811:
  [ticket/10811] Make toogle_subscribe more generic so it can toogle all links
  [ticket/10811] Make it easier for MODs/Extensions to define the alt-text
  [ticket/10811] Make subscribe/unsubscribe repeatable with AJAX
  [ticket/10811] Fix AJAX callback alt_text so it can be repeated.
[feature/postgresql-fulltext-search] Remove closing php tag

PHPBB3-9730
[feature/postgresql-fulltext-search] Fixed braces

Fixes braces in fulltext_postgres.php to comply with phpbb conventions.

PHPBB3-9730
[feature/postgresql-fulltext-search] minor changes

Some changes in code to get it work against current develop.
PosgreSQL Fulltext search works for new install now.

PHPBB3-9730
[feature/postgresql-fulltext-search] database changes in database_update

config entries are now added by database_update.php as well.
PostgreSQL will work during update too.

PHPBB3-9730
[feature/postgresql-fulltext-search] minor changes

Changes to comply with other backend conventions. include $user as global
variable to access it inside init();

PHPBB3-9730
[feature/postgresql-fulltext-search] remove backward compatibility

removes backward compatibility before PostgreSQL ver 8.3
if version is before 8.3 displays error.

PHPBB3-9730
[feature/postgresql-fulltext-search] assign empty stats

Blank array is assigned to stats incase pgsql fulltext
search backend is not compatible

PHPBB3-9730
[feature/postgresql-fulltext-search] fixing license

PHPBB3-9730
[feature/postgresql-fulltext-search] Fix version comparison for 9.0+.

PHPBB3-9730
[feature/postgresql-fulltext-search] fix variable name

Variable name used is now tsearch_usable instead of tsearch_builtin
to reflect its actual purpose.

PHPBB3-9730
[feature/postgresql-fulltext-search] use phpbb_pcre_utf8_support()

Use phpBB's built in function for checking PCRE lib support.

PHPBB3-9730
[feature/postgresql-fulltext-search] change language for pgsql < 8.3

PHPBB3-9730
[feature/postgresql-fulltext-search] remove mbstring support

Remove the usage of mbstring regex engine when PCRE does not support UTF8
since its a requirement for phpbb 3.1

PHPBB3-9730
[feature/postgresql-fulltext-search] fix language tsearch2 to text search

Language is changed according to the current PostgreSQL documentation.

PHPBB3-9730
[feature/postgresql-fulltext-search] removes pcre check

PCRE UTF8 support is already checked globally. adds an option of
pgsql version to acp.

PHPBB3-9730
[feature/postgresql-fulltext-search] remove Readme

PHPBB3-9730
[feature/postgresql-fulltext-search] fix language key

Language key name not incompatible_database instead of version which
was misleading

PHPBB3-9730
[feature/postgresql-fulltext-search] use version_compare

version_compare is used for version comparision and pgsql version is now
a global variable that is displayed in the acp too.

PHPBB3-9730