Closes #39.

it could be neat and there'd be s/kids/children/ — Oh well.

correctly. Since a list section pushes a sub-object of the
"view" into the "current" context, a partial should recognize
this altered context. The one-line change in mustache.js does
exactly this.

Closes #35.

This reverts commit c2f886602af6ff2d6790b33f87445fc2a5677e0e, reversing
changes made to 88d3d9cf32.

This reverts commit f1f55138a4.

If a section key returns a function, it will be called
and passed both the unrendered block of text and a renderer
convenience function.

Given this JS:

  "name": "Tater",
  "bolder": function() {
    return function(text, render) {
      return "<b>" + render(text) + '</b>'
    }
  }

And this template:

  {{#bolder}}Hi {{name}}.{{/bolder}}

We'll get this output:

  <b>Hi Tater.</b>

As you can see, we're pre-processing the text in the block.
This can be used to implement caching, filters (like syntax
highlighting), etc.

You can use `this.name` to access the attribute `name` from
your view.

Changing the delimiter and use the new one on the
same line was broken. Fixed that and extended the
test suite.