node auto-keywords: take from vocabulary

On the issue Valid description & keyowrds for category pages, robrechtj wrote:

As for folksonomy. This is just a vocabulary as another. I will add to "nodewords - settings" an option to use a specified (folksonomy enabled?) vocabulary instead of an input box for keywords.

Auto-keywords is a great option which will save tons of time to the person who manages the content. It doesn't matter if the node's vocabulary is folksonomy-enabled or not - auto-keywords is aleays a great feature. If a node is attached to three different vocabulary terms, those terms are an excellent base for an automatic keywords list.

It will be great to allow auto-keywords for all nodes. I suggest the following configuration option:

• Auto-keyword vocabularies (selection list)

The user will select vocabularies for auto-keyowrds. Nodewords will auto-append terms from the selected vocabularies into the node keywords list.

Notes:

• The first keywords should always be the keywords manually selected in the nodewords field (if any), since those are the main keywords and the search engines must see them first.
• Don't repeat keyowrds which already exist since this is called keyword-stuffing by the search-engines. If the drupal user added a keyword which already exist in the list (e.g. zzz), it's a sign that the user wants to see this keyword first, on the top of the list.
• Druring the keywords meta-tag generation, only search the vocabularies valid for the node type.