cmd/guru: rename oracle to guru, copying it to a single package
cmd/guru: rename oracle to guru, copying it to a single package

See plans at:
https://docs.google.com/document/d/1UErU12vR7jTedYvKHVNRzGPmXqdMASZ6PfE7B-p6sIg/edit#heading=h.t5rbcuy7di7j

Change-Id: I369747e0ce8cd42a2975eb0f651a2e5fba47cf9e
Reviewed-on: https://go-review.googlesource.com/19475
Reviewed-by: Alan Donovan <7069e9552f9d110b0a0f326b96f22f63fb99dfc1@google.com>

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