Slice arcs that are larger than 180 degrees will overlap previously drawn slices

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If a piechart has a large slice that takes up more than 50% of the piechart the filling of the arc shape might overlap previous slices.

It can be solved by checking if the to be drawn slice has a start and end difference > 180 in the _drawSlice function. If so I divide the slice in 2 parts and draw those using the same _drawSlice function.