TextBundle discussion

Hey @uranusjr and others,

First of all thanks for making a great app, I am thoroughly enjoying working with it!

As for my question; I recently came across a specification for a 'new' file-format called [TextBundle](http://textbundle.org) which aims to improve the way Markdown files and its assets are versioned and organised. This concept really resonated with me since I always struggle with said organisation. Therefore I would like to initiate a discussion whether or not MacDown should support this.

Check out the [TextBundle specification](http://textbundle.org/spec/) and please leave your comments below. Thanks!

Start with the linked TextBundle specification and then inspect MacDown’s existing Markdown and asset/file-handling entry points; the issue names no files or tests. Establish whether support is in scope, define the supported behavior and acceptance criteria, and confirm the discussion has a concrete implementation target before beginning.

Written by the indexing model from the issue text.