The performance of the previous implementation was simply horrible,
when drawing an arc with a small span angle. The size of the corresponding full circle
is huge and the previous implementation always created an image/texture with
that size.
However the final implementation is supposed to create vertex lists
- like what the box renderer does. So this code will also not stay forever.
* add QskArcNode and QskArcRenderer
* IOT example: Use QskArcNode instead of own arc node
* move some functionality to the arc renderer
* add QskArcMetrics
* add methods to QskSkinlet
* remove circular bar graph node
We can now use updateArcNode() and don't need our own method.
* support linear gradients in the arc renderer
* clean up
* incorporate Uwe's changes
* add overloads for updateArcNode() when the angles are set dynamically
The angles don't always come from the style, so we need overloads
in QskSkinlet to set them dynamically.
