Update/add faces

- Change "#ff756e" to "#e09591" to make it stand out less.
- Make the `font-lock-warning-face' orange to make it stand out more,
  now that the red color has been made to stand out less.
- Add `highlight-80+' face.
- Add `identica-mode' faces.
- Remove the background from `magit-item-highlight'.
Make visited links violet