Add lib/keyboard.coffee
Keyboard extends Sprite

This way, a keyboard is just another Turtle that you can move around
on the screen just like any other turtle, for fun and nice visual
effects.
Speed up keyboard using canvas drawing.

Turtle drawing is slow, so this rewrite expresses the keyboard
drawing using raw canvas drawing.  It now preforms acceptably
well in Firefox.
Friendlier constructor for Keyboard
More muted colors.
Merge pull request #70 from PencilCode/keyboard

Add lib/keyboard.coffee