nodecomment_get_comment_types() returns array with blank key/index every time

The function nodecomment_get_comment_types should return an array of all content types that utilize nodecomment for commenting. The current logic is incorrect in that it will almost always return a blank key/value pair in the returned array, because it doesn't check to see if the cycled thru content type actually implements nodecomment or not.

Patch coming to fix...