Including Markdown Flavours Features

Hi,

I’d like to say I find the initiative awesome and fully support the way of first cleaning Markdown into a spec.
I would also like to propose adding the extra features from flavoured Markdown, like the one from Github.
This features were obviously missing for certain user groups.
If for v1 your are concentrating only on cleaning Markdown then maybe v2.
I’d be interested in helping, if joining is possible.