TexScatter: Added Radial Fades, fixed Inverts, broke importance

++ Radial Fade for all textures
++ Fixed missing Tex Inverts on Tex B,C,D
-- texture importance is broken after switch to steppedFBM from udnVor.
Revisit or switch back (slow !)
-- Investigate Convert to Paintable crashes
-- clean up unused functions in header
-- clean up unsed variables
-- clean up code visually
-- per layer value attenuation
-- improve noi seeding
-- add varying cell size (might not be possible ...)
-- add 3d projection of cells
-- investigate faint grid lines in texture ??