Tmux: Bind C-a r to config reload

Tested-by: Ratheesh S <ratheeshreddy@gmail.com>
Signed-off-by: Ratheesh S <ratheeshreddy@gmail.com>
Emacs: customize colors for diff-mode

Tested-by: Ratheesh S <ratheeshreddy@gmail.com>
Signed-off-by: Ratheesh S <ratheeshreddy@gmail.com>