internal/gen: added Write*Version

Added for consistent version writing.

Added to all applicable package that do not already have conflicting
version constants.

This is needed to make the tests in the repo more resilient to
Unicode changes and will be generally useful.

Change-Id: Ia34c3a32c458f2cc7c3503a21b3a78b8dd348c28
Reviewed-on: https://go-review.googlesource.com/11993
Reviewed-by: Nigel Tao <nigeltao@golang.org>
10 files changed