This fixes the following usability issues:
- when go-guru is called twice in a row and the output from the second invocation
is bigger then this output is not fully visible
- output window could be re-used by other packages (such as helm) that are not
usable with the shrank window
Change-Id: I86d522006d29e945a71b96c9d13a1a39572bdb3b
Reviewed-on: https://go-review.googlesource.com/19780
Reviewed-by: Dominik Honnef <dominik@honnef.co>
Reviewed-by: Alan Donovan <adonovan@google.com>