Enhancement for later

[szczepanskiNicolas]

• Add a new button to save all layers of all images
• Option on eraser to erase all label at the same time
• Option on clear all to erase all label at the same time
• In coutour filling, the possibilty to delete an already fill area with one click
• Different type of brush for the paintbrush

[szczepanskiNicolas]

• Limit the brush size of the paintbrush and the eraser tools to have a size with a pair number to avoir a shift of pixels