gh-935

**not ready for merge**

Right now this takes care of generating the right output format - consuming it is another matter
Actually that's one of the reasons I was thinking it probably makes sense *not* to have `ractive.template` - we're not all that consistent about which properties of `ractive` are designed to be read, which are designed to be written, and which are purely for internal use.

But yeah, it's an academic concern for the most part. Reckon we're ready to ship?