Merge branch 'dev' into 'main'

README.md

android/build.gradle

android/google-services.json

android/local.properties

android/src/com/ratattack/game/AndroidInterfaceClass.java

android/src/com/ratattack/game/AndroidLauncher.java

assets/arrow.png

assets/background_dark.png

assets/background_light.png

assets/badlogic.jpg

assets/btn_back_to_menu.png

assets/btn_highscores.png

assets/btn_no_upgrade.png

assets/btn_play.png

assets/btn_play_tutorial.png

assets/btn_quit.png

assets/btn_small_pause.png

assets/btn_small_play.png

assets/btn_tutorial.png

assets/btn_upgrade_big_bullet.png