Update tmux aliases

- Make 't' either connect to the session named after the $PWD, or make a
  new sessions named after the $PWD
- This removes the need for some other aliases
Mutt: consistently swap d/C-d and u/C-u
Emacs: add writegood mode

More info: https://github.com/bnbeckwith/writegood-mode
Mutt: fix index display for console fonts