This allows arguments to be passed along in an $allowed_actions deceleration of
the form 'action' => '->method' in the same way that arguments can be passed to
extension constructors when adding them using $extensions or
Object::add_extension.
I.e. 'action' => '->checkerMethod(false, 7, 2, "yesterday") would call the
checkerMethod method with the boolean false the numbers 7 and 2 and the string
"yesterday" as its arguments.
