Change how View_Theme sets "item" and "tag" as null from local to global.
This is because View::__get() uses array_key_exists(), not isset().  So, a local
null will trump a global non-null.
Fix Request calls to non-static methods (e.g. "Request::foo()" --> "Request::$current->foo()")
Update ORM "->join()" syntax to "->join()->on()" (19 places).
Correct quotes and as_object flag in Search.  Still need to fix ORM_Iterator references.
Update Gallery::find_file() to remove required argument (not in K3).
Fix references to ui.init.js --> screen.js