Check teaser and body before smart tagging

The code in delicious_nodeapi() calls _delicious_tag_text() for both $node->body and $node->teaser. However, almost always only one of them is the right one to process. The other will be empty.

When this happens, _delicious_tag_text() unnecessarily loops on all the tags passing an empty $text variable to a preg_match().

Attached a patch which does an emptiness check in delicious_nodeapi() before processing.