Update code order (.emacs): Move functions before external imports so they can also be used by custom .el files.
Fix bug (.emacs): Remove non-working previous-window() function to a built-in emacs command: previous-multiframe-window.
Add new feature (codes.el): Change "bash" to "zsh".
Add function (keys.el): Add new function multi-term-emacs-lisp-custom-keybindings() for term-mode keybindings.
Add commands (setup.sh): Add new system commands to install zsh, and zsh customizations.