language: added PreferSameScript MatchOption

and added match options.

Change-Id: I7c772740515ff557b30fa03be034622b49ea544a
Reviewed-on: https://go-review.googlesource.com/47592
Run-TryBot: Marcel van Lohuizen <mpvl@golang.org>
Reviewed-by: Nigel Tao <nigeltao@golang.org>
2 files changed