Clean / improve / update code

assets/fonts/Nunito-Bold.ttf

assets/fonts/Nunito-Light.ttf

assets/fonts/Nunito-Medium.ttf

assets/fonts/Nunito-Regular.ttf

assets/icons/button_restart.png

assets/skins/default_tile.png

assets/translations/en.json

assets/translations/fr.json

assets/ui/button_back.png

assets/ui/button_delete_saved_game.png

assets/ui/button_resume_game.png

assets/ui/button_start.png

assets/ui/empty.png

assets/ui/game_fail.png

assets/ui/game_win.png

assets/ui/placeholder.png

fastlane/metadata/android/en-US/changelogs/20.txt

fastlane/metadata/android/fr-FR/changelogs/20.txt

icons/button_back.svg

icons/button_delete_saved_game.svg