bitmap smudge: added alpha color + circular cursors visibility enhancement
popup color palette updates and some code simplification
Merge pull request #194 from eVoLuTiVeMEDIA/master

Bitmap smudge alpha  fix & some updates
Smudge 2nd mode = hard ( by pressing [alt] ).

Useful for painting & photo-retouches.
Smudging while pressing [alt] produces a hard (non smoothed) pixel
displacement. Normal smudge can be combined to smooth the result.
Will be improved to get a complete non-pixel-destructive liquify.
Merge pull request #196 from eVoLuTiVeMEDIA/master

Smudge 2nd mode = hard ( by pressing [alt] ).
smudge brush: small precision improvements

1. Smoother smudge.
2. Smoother liquify smudge ( [Alt] in smudge mode ) now it works better
with transparencies
Liquify is better tested on photographies, or opaque illustrations
Merge pull request #197 from eVoLuTiVeMEDIA/master

smudge brush: discreet precision improvement
Final adjustments for smudge + hints + resources
Merge pull request #198 from eVoLuTiVeMEDIA/master

Some improvements for smudge + hints + resources
Merge branch 'master' into feature/object-save-loader
Merge branch 'feature/object-save-loader' of https://github.com/chchwy/pencil2d into feature/object-save-loader