Include raw references
Copy the kramdown-2629 citation index (somewhat)

Allow inclusion of raw XML citations, detect them and add them to
the citation list. The negates the use of filenames in the citations,
so that could also be dropped.

Started writing document on how to use mmark: mmark2rfc.md
updates
Add more documentation.

Change cref seperator from : to --, this is more inline with the
Quote caption.