Drawing is slow. Should be using Uint8ClampedArray

[ticky]

Info: https://hacks.mozilla.org/2011/12/faster-canvas-pixel-manipulation-with-typed-arrays/

[gingerbeardman]

FYI measurements from https://jsperf.com/canvas-pixel-manipulation on my system show that currently drawing is 20–50% slower than it could be using Uint8ClampedArray.