Support optional markdown formatting in recipe description body

[ilveroluca]

This is a feature request.

I think it would be useful to have some sort of simple formatting support for the text in the recipe description. Markdown seems like a good option for this. The implementation could leverage one of several existing JavaScript markdown editors and/or renderers, to be embedded in the front-end interface to provide support for editing, previewing and viewing.

What you expected to happen

On the recipe editing page, there would be a new control (maybe a checkbox) to enable / disable markdown support for the recipe. If enabled, the markdown editor would appear, and the recipe description text would be interpreted as markdown when rendering for viewing. Optionally, if a suitable editing module is found and adopted, WYSIWYG editing could be provided.