I've long been hoping (not being a programmer myself) that someone would get around to writing the heading folding functionality. Your implementation works quite well from what I can tell from my quick testing.
One feature request: is it possible to preserve the folded state of subheadings? I.e., if I fold and un-fold
# then all the
## are folded up, even though some of them might have been unfolded previously. I hope this description makes sense.
Also, the folding functionality doesn't play very well with the command palette (I mean Ctrl/Command+R). It unfolds everything.
The bullet-complete is missing support for nested lists and blockquotes. I also came across a bug. To reproduce, write this:
Placing the cursor between A and Z and pressing ENTER will generate asterisks without changing the line (on Ubuntu 12.04, ST2 buid 2203).
What kind of thing do you have in mind to do in relation with Pandoc? I have a build system that works with MultiTaskBuild that I've been meaning to convert to Sublime's new variant build system. But other than that I can't think of any other way to combine the two.
I have read about but not used Org-Mode (I've never managed to get into Emacs). What aspects are you interested in porting to Sublime?
Off the top of my head, opening links with ENTER would be a welcome feature for Markdown files. I obviously mean http links, but I would like to see local file support. (I would really like to be able create files that act as indexes to other files.)
I write quite a lot in Markdown and there is, I think, a lot of functionality that would be useful to bring to Sublime. I look forward to the development of this plugin.