Improve Silverefx

Improve silverefx as the preeminent BW conversion tool.

Agree. Much needed are more B&W film emulations, including better faux infrared.

Individual color response sliders.

An adjustable vignette tool as opposed to the current On - Off function.
Size, strength, feathering, and selecting a center point.
This could benefit any of the modules but I’d find it especially useful in Silver Efex.