flag: add Getter interface (CL 10472043).
fmt: indexed access to arguments in Printf etc. (CL 9680043).
go/build: support including C++ code with cgo (CL 8248043).
+image/draw: added Drawer, FloydSteinberg and the op.Draw method (CL 10977043).
+image/draw: added Quantizer type (CL 11148043).
+image/gif: added Encode and EncodeAll (CL 10896043).
io: Copy prioritizes WriterTo over ReaderFrom (CL 9462044).
net: new build tag netgo for building a pure Go net package (CL 7100050).
sort: new Stable function provides stable sort (CL 9612044).