[bash_aliases] update ruby version
[environment] support linux and osx; add git support to PROMPT
whitespace
[git] whitespace; add `git pull-theirs`
[install] whitespace; add to ignore directories
[osx] add macbook key layout tweaks

needs to be manually copied to `/Library/Keyboard\ Layouts/` and then system rebooted.
[bash] add some colour variables
[emacs] update cl-mode
[emacs] update d-mode
[emacs] update hl-mode
[emacs] update tuareg
[emacs] update python-mode
[emacs] update org-mode
[emacs] update markdown-mode
[emacs] update gh-mode
[emacs] update pcache
[emacs] remove updated cl-lib and diff-hl
[emacs] package contents update