filter/dynamic-mask: Replace rendering code and optimize storage

The rendering code here was one of the older code bases, which was riddled with bugs and leaks. The new code doesn't look pretty, but it works for the time being until a better solution is found or made. It should be able to handle HDR inputs now, but it may not be completely correct yet. This also fixes the double-free bug.

As an additional improvement, I've moved the allocation of the effect to a shared class which should reduce the memory usage slightly when multiple effects are in play. And now selecting nothing selects the filter target itself without infinitely adding references to the filter. Good enough in my eyes.

Fixes #819

data/locale/en-US.ini

@@ -392,6 +392,9 @@ Filter.DynamicMask.Channel="%s Channel"
 Filter.DynamicMask.Channel.Value="Base Value"
 Filter.DynamicMask.Channel.Multiplier="Multiplier"
 Filter.DynamicMask.Channel.Input="%s Input Value"
+Filter.DynamicMask.Debug.Texture="Debug Texture"
+Filter.DynamicMask.Debug.Texture.Base="Base"
+Filter.DynamicMask.Debug.Texture.Input="Input"
 
 # Filter - SDF Effects
 Filter.SDFEffects="SDF Effects"