exp/draw: add Point.Eq, Point.Mul, Point.Div, Rectangle.Size methods
exp/draw: add Point.Eq, Point.Mul, Point.Div, Rectangle.Size methods

R=nigeltao, nigeltao_golang, rsc
CC=golang-dev, r
http://codereview.appspot.com/2192048

Committer: Nigel Tao <58ae08b3356928ff9c67562b4719487d54fe8348@golang.org>

gnanderson/go,h8liu/golang,ssrl/go,gnanderson/go,dsriram/golang,tv42/old-go,ssrl/go,apparentlymart/golang,apparentlymart/golang,tv42/old-go,ssrl/go,ssrl/go,apparentlymart/golang,tv42/old-go,pombredanne/go-deleteme,dsriram/golang,h8liu/golang,h8liu/golang,gnanderson/go,h8liu/golang,pombredanne/go-deleteme,pombredanne/go-deleteme,pombredanne/go-deleteme,h8liu/golang,dsriram/golang,tv42/old-go,pombredanne/go-deleteme,tv42/old-go,h8liu/golang,apparentlymart/golang,ssrl/go,ssrl/go,apparentlymart/golang,ssrl/go,gnanderson/go,pombredanne/go-deleteme,dsriram/golang,gnanderson/go,dsriram/golang,dsriram/golang,gnanderson/go,apparentlymart/golang,tv42/old-go,apparentlymart/golang,dsriram/golang,pombredanne/go-deleteme,tv42/old-go,gnanderson/go,h8liu/golang