Fastest Auto Levels substance node

This is a super-duper fast auto levels node made with pixel processor's chain, the alghorithm is identical to the original one but much faster due to heavy using of vector sampling and computation. This node is up to 25-40 TIMES FASTER than an original auto_levels and up to TWO TIMES faster then auto_levels_plus with enabled optimizations (reducing each node resolution by factor two) AT FULL 8K RESOLUTION.