fix a bug that does not remove array overlay in /insertat/ module.

- fix an error on sunrise configuration
modify the org agenda directory from "~/.emacs.d/agenda" to "~/agenda"

- If the agenda directory is a symbolic link to the Dropbox directory,
  auto-save files are in /tmp/ by updating
  `auto-save-file-name-transforms`.
add `ess-shell`, that invoke R and switch to the buffer
add support for AMS style equation numbering with MathJax.
add `ess-dev-off` and its shortcut to call `dev.off()`
Merge remote-tracking branch 'refs/remotes/origin/master'
update the packages URL *melpa*