Introducing Method createEquallyDividedPie()

- redesigned the handling of the wrapping div and the background-div
holding the slices. I think I got it mor encapsulated now.

createEquallyDividedPie(...) returns a div containing the pie as
createPie does. It takes the same parameters minus the
percentages-Array. The Colors Array gets looped over if there are too
few colors in there for all the slices.