Add support for more operator overloads.
Add SkSurface, SkPoint, SkIPoint, SkIPoint16 docs.
(SkImage doc skeleton added, but not really started.)
Force recompile all examples.
Docs-Preview: https://skia.org/?cl=67726
Bug: skia:6898
Change-Id: If9e2d23f79d5db64146dd22588f5cac970614b8a
Reviewed-on: https://skia-review.googlesource.com/67726
Commit-Queue: Cary Clark <caryclark@google.com>
Reviewed-by: Cary Clark <caryclark@google.com>
