* Initial implementation of paint effects
* Improving HasPaint
* Adding color effect
* Adding exaustive tests for the HasPaint mixin
* Adding tests for the effects
* some adjustments
* Fixing some imports
* Adding docs
* Adding types to the has paint mixin
* Fixing constructor name for the opacity effect
* Apply suggestions from code review
Co-authored-by: Luan Nico <luanpotter27@gmail.com>
* Luan's suggestion
* Luan's comments
* formatting issues
* dartcodemetrics don't help me :(
* Adding assert
Co-authored-by: Luan Nico <luanpotter27@gmail.com>
