This is an experimental command that perhaps would become "go new"
once we have more experience with it. We want to enable people to
experiment with it and write their own templates and see how it works,
and for that we need to put it in a place where it's reasonable to ask
users to fetch it from. That place is golang.org/x/tools/cmd/gonew.

There is an earlier copy in rsc.io/tmp/gonew, but that isn't the right
place for end users to be fetching something to try.

Once the tool is checked in I intend to start a GitHub discussion
asking for feedback and suggestions about what is missing.
I hope we will be able to identify core functionality that handles a
large fraction of use cases.

I've been using the earlier version myself for a while, and I've found
it very convenient even in other contexts, like I want the code for a
given module and don't want to go look up its Git repo and so on:

	go new rsc.io/quote@v1.5.2
	cd quote

Change-Id: Ifc27cbd5d87ded89bc707b087b3f08fa70b1ef07
Reviewed-on: https://go-review.googlesource.com/c/tools/+/513737
gopls-CI: kokoro <noreply+kokoro@google.com>
Run-TryBot: Russ Cox <rsc@golang.org>
Auto-Submit: Russ Cox <rsc@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>