Missing Markdown

Thank you, 1P_SimonH.

If a fuller support of Markdown is challenging, then the one most significant missing item is `code` for a fixed-width typeface. This should be the simplest to implement.

This is made more challenging by the editor offering "Preformatted" in the drop-down for new posts (and only for paragraph style), but offering only a minimal subset of the formatting toolbar for replies where Markdown and shortcuts offer different subsets of features.