[Automatic Type Popup] fix + remove type prefixes

[rvion]

related to #26

[tomv564]

I fixed the tests and then turned the region highlighting back on, too. I think it can be merged, unless the plan was to turn the region highlighting off.

[rvion]

thanks you very much !
No, the plan was not to turn the region highlighting off, I just hacked something quickly last time.

Before merging, I also need to fix the shorten_module_prefix function so it works with types like

undefined :: x1 -> (A.B.x2 -> [B.C.x3]) -> x4

For now, the opening parens: '(' and opening bracket: '['sare not properly kept

I'll push the fix tomorrow

[rvion]

Automatic type popup on hovering now replace qualified type prefixes by an "_" to help readability.
Hitting Cmd+T still display the type as it was before, so one can still ask the editor where do the types comes from.

It should only affect those using the automatic type popup

example

• with the show type command/shortcut:
  
• with the automatic type popup