Sharper canvas, PSD adjustments and masks, Photoshop's Saturation, Levels and Hue/Saturation on every core, a growing blur's preview kept, the hierarchy kept (13.8)

kernels/LevelsPixels.h

@@ -2,3 +2,4 @@
 #include <stddef.h>
 void levels_apply(uint8_t *pixels, size_t count, const float *tables);
 void levels_histogram(const uint8_t *pixels, const uint8_t *coverage, size_t count, double *bins);
+void cube_apply(uint8_t *pixels, size_t count, const float *cube, int dimension);