Add information to the template methods (empty, header and footer) that ...

...indicates the kind of results producing the template call. This allows templates such as the 'empty' template to take action based on whether the results have come from a clear, from a cache hit in bloodhound, from a remote server, etc.

Some good usage examples:
- A client may choose to only display the empty message when the full roundtrip from the server has completed, indicating that there truly are no results.
- A loading message can be displayed in the footer to indicate that additional results are coming from the server.