this currently creates `this.tmpl['contact-tmpl']` and `this.tmpl['highlight-tmpl']` instead of `this.tmpl.contact` and `this.tmpl.highlight`.

Here is my proposition for your template API:

* keep `create` but make it take only one id, and return a Utils.Template implementation instead of the current array of node.
* get rid of `prepare`, we don't really need it (I suppose you wanted to call it in `create`)
* move `extract` as an internal function
* move `interpolate` to `Utils.template.prototype`

Except this doesn't look like the implementation planned in ES6, it seems to me it would be easier to use.

At the very least, I want `create` to only take one id and return something for this id. The OO approach seems better to me for this, but if you prefer to keep the procedural approach that would be fine to me too.