cmd/guru: emacs: add default key binding for whicherrs
cmd/guru: emacs: add default key binding for whicherrs

Bind go-guru-whicherrs to `C-C C-o e'

Also remove go-guru-callgraph as callgraph mode is not supported
by guru.

Change-Id: Id233d178629a3cafc00e4f9640191c3d3c673cf1
Reviewed-on: https://go-review.googlesource.com/20310
Reviewed-by: Alan Donovan <7069e9552f9d110b0a0f326b96f22f63fb99dfc1@google.com>

dominikh/go-mode.el,emacsmirror/go-mode