Changed Rectangle to Rect
update canvas
scaleX and scaleY default value changed to 1

Changed Ball constructor to Circle, removed unnecessary close path in
Circle.draw, change scaleX and scaleY default value to 1, because 0
prevents the shape from appearing on the canvas.
Added radians function

converts radians to degrees
changed rotation to angle in arrow constructor
Merge pull request #2 from james99b/dev

Dev