Show types only for values (on hover) and unapplied functions

Instead of showing types all the time this commit only shows types when there’s no output (i.e. unapplied functions) and return values when hovering over those values.

This image shows what it looks like (element with yellow background is hovered over)
![Try Haskell hover types](https://cloud.githubusercontent.com/assets/679122/3138922/643980d2-e8b9-11e3-8e52-2f247373966d.gif)