Feature.module fixed

The feature.module navigation was wrong and not working I have fixed it and since changed it to the expected tab behaviour. There should be an updated made on it's installation to reflect the need to use a page and PHP evaluated code to the effect of

print feature_listing();

I have also changed

check_output($categories[$feature->category])

to

$categories[$feature->category]

As the check_output function conflicts with a HTML filter and causes a line break to become a P tag surrounding the title on printing to the screen. But does not show otherwise.