They were causing issues with UndoRedo, and with the latest changes, even crashes. I decided to remove their UndoRedo behavior, at least for now.
Also put jegor377 to the list of Contributors.
- If the palette has colors, automatically select the first one
- When adding a new color button, take the color currently selected on the picker instead of white
- Fixes issues with drag&dropping color buttons. The color that was dragged remains selected.