plasticboy/vim-markdown — pull request #120 by cirosantilli (2014-09-05 22:48:09+00:00)
Title: Use stdm.

With GitHub + Stack Exchange + Reddit support + 2 reference implementations it will dominate.

http://jgm.github.io/stmd/spec.html

Furthermore, it is currently a good average of existing implementations, and much better specified than the original markdown.