QskGradientIterator

[uwerat]

Would be have a specific iterator for the gradient stops so that application code can iterate without having to deal with:

• missing stops at 0.0/1.0 ( -> colors are take from the first/last stops then )
• inverted iteration - f.e useful, when having an decreasing linear gradient vector
• discrete iteration: sometimes a gradient with fixed colors between the stops ( no interpolation ) is wanted. Today it is necessary to insert 2 stops at the same position.