[TxMt] Markdown bundle

[hadley wickham]

> keyword.other.markdown is currently wrong, but at least then it gets
> assigned a style by default -- probably it should be
> constant.<something>.code.markdown. Maybe that's stretching constants
> a bit though.

I was thinking something like markup.raw to indicate that it's not
processed by markdown.  This would also be applicable to other markup
systems (eg. textile) which do similar things.

> Starting with beta 9 it should be possible to do something like:
>     begin = "..."; end = "^$";
> 
> And that'll require one blank line to end the construct. I think this
> was required for headers!?!

Great! That will also work will for matching the various lists which
can run over multiple lines.

Hadley