Experiental support for generating multiple output formats from the
same siphoned data.
Adds a contrived example to generate a plain list of all CLI commands
(the "itemlist" format).
Eventually we can consider moving the tempate procesisng into the
Output class as well as a way to override how the data is traversed
(ordered).
Change-Id: I77629a74a8fa0c7e583993469dc50491f72f13e7
Signed-off-by: Chris Luke <chrisy@flirble.org>
