Allow custom layouts to be set in page meta. From the @pomaxa fork.

Now you can do this:

    /*
    Title: I Love Kittens
    Author: James Doyle
    Layout: post
    */

This will load the `post.html` file from your chosen theme. If the `Layout` key was absent it would just fallback to the `index.html` file.

Taken from @pomaxa's fork!

This feature is in a couple other forks and I believe it is strongly needed.