I have installed markdown-mode.el as described here. How do I get Emacs (specifically, Aquamacs) to load gfm-mode rather than markdown-mode for .markdown files? In case it's important, the relevant section(s) of my ~/.emacs currently look(s) like this:
(add-to-list 'load-path "~/.emacs.d/")
; Some irrelevant (I think) other stuff
(autoload 'markdown-mode "markdown-mode.el" "Major mode for editing Markdown files" t)
(add-to-list 'auto-mode-alist '("\\.text\\'" . markdown-mode))
(add-to-list 'auto-mode-alist '("\\.md\\'" . markdown-mode))
(add-to-list 'auto-mode-alist '("\\.mdown\\'" . markdown-mode))
(add-to-list 'auto-mode-alist '("\\.mdt\\'" . markdown-mode))
(add-to-list 'auto-mode-alist '("\\.markdown\\'" . markdown-mode))
I'm extremely noobish with Emacs in general, so I'd appreciate step-by-step instructions.