Inverted mask: user interface improvements - and linking inverted masks

When a mask is inversed, there is no obvious indication that a mask is inversed in its pedigree.

  • The list of local customizations in the local adjustments sub-palette should have a symbol linking the original mask and its inverted twin, and clearly showing the base and derived mask.
  • When using control-point masks, the positive control points and negative controil points are displayed the same in the original mask and in the inverted twin. The control point symbols (negative and positive) should be swapped.
  • When masks are related by the inversion function, modifying one should modify the other, unless the two masks are unlinked.