Similar color selection tool modernize
First commit: just add another option to the tool (it's already working) Second: make it multithreaded (in commands) Third: optimize
Problem in the MR:
- Color Labeled Layers is restrained to the image bounds (in theory it's fine, since it's a new feature, but...)
- Some solution: area inside the image bounds would be calculated in the optimized way as it is now, but later I could add one or more strokes that would just take care of the sides (it would be not 100% optimized but still much more than it is before this MR, and it would allow for calculating everything even outside of the image bounds).
- Dmitry talked about some other way, but I'm not sure how to do it without leaving the applicator + commands as the way to approach multithreading (and I would prefer to keep it consistent between selection tools).
test file: conti_color_new_options_002.kra
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