Initial commit of filter support feature.

Proper attribution, and testing is needed.
	modified:   controllers/Sources.php
	modified:   daos/mysql/Database.php
	modified:   daos/mysql/Sources.php
	modified:   daos/pgsql/Database.php
	modified:   daos/pgsql/Sources.php
	modified:   daos/sqlite/Database.php
	modified:   daos/sqlite/Sources.php
	modified:   helpers/ContentLoader.php
	modified:   public/lang/en.ini
	modified:   templates/source.phtml