Fixed php error for "in" operator

I have added the tests and also fixed the php error ``An exception has been thrown during the rendering of a template ("strlen() expects parameter 1 to be string, array given")``.
All of these tests are for documentation of confusing behaviour of "in" operator. In my opinion the ``resource`` type should not be in ``string`` type, as in the current implementation (similar to ``{{ dir_object in 'foo'~dir_name ? 'TRUE' : 'FALSE' }}`` - an object in a string).