markdown mode and polymode for emacs Rmd support

polymode

;; obtain from http://jblevins.org/projects/markdown-mode/

 (load "~/path/to/markdown-mode.el")
 (autoload 'markdown-mode "markdown-mode"
   "Major mode for editing Markdown files" t)
 (add-to-list 'auto-mode-alist '("\\.md\\'" . markdown-mode))

;; obtain from https://github.com/vitoshka/polymode

 (setq load-path
       (append '("~/path/to/polymode/"  "~/path/to/polymode/modes")
               load-path))
 (require 'poly-R)
 (require 'poly-markdown)
 (add-to-list 'auto-mode-alist '("\\.Rmd\\'" . poly-markdown+r-mode))