Render the content of a specific block tag from a Django template

 Render the content of a specific block tag from a Django template. Works for
 arbitrary template inheritance, even if a block is defined in the child
 template but not in the parent. Generally it works like render_to_string
 from Django, but allows you to specify a block to render.
 .
 Features:
 .
  * Render a specific block from a template
  * Fully supports the Django templating engine
  * Partially supports the Jinja2 engine: it does not currently process the
    extends tag