This change removes support for Go 1.8 and older, as they're no longer
supported per release policy¹.
This brings back a simpler file layout that was here prior to CL 36730,
but keeps using type aliases for the exported names from the standard
library's image/draw package.
Don't keep the comment motivating type alias use, since that feature is
no longer new, and commonly understood by now.
¹ https://tip.golang.org/doc/devel/release.html#policy
Change-Id: I5fab71162cf6daa5985a048ed06011efacddf886
Reviewed-on: https://go-review.googlesource.com/c/148567
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This is the golang.org/x equivalent of the golang.org/cl/36732 change to
the standard library.
Change-Id: I71c09a72e24c8e1c013769a6fed8f9a031724d9d
Reviewed-on: https://go-review.googlesource.com/36733
Run-TryBot: Nigel Tao <nigeltao@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
