Squashed commit of the following:

commit 6bb706dfd79cf11f840c7b0ed05b12e30efd7176
Author: Cédric Néhémie <cedric.nehemie@gmail.com>
Date:   Mon Dec 30 11:39:32 2013 +0100

    Add joinExt option

    When joining many literate CoffeeScript files, the generated
    joined file still use the `coffee` extension. The joined
    file can't be compiled or documented properly due to that.

    Passing `.src.litcoffee` or `.src.coffee.md` in `joinExt` fix it.

Closes gh-108.
Update docs, bump to 10.1