grass.jpg	https://opengameart.org/node/10183
ground.jpg	https://opengameart.org/node/10180
skyline.png	https://opengameart.org/content/skyline
bird        https://opengameart.org/content/bevouliin-free-game-character-grumpy-bird
FER_logo.png	https://www.fer.unizg.hr/_pub/themes_static/fer2016/default/img/FER_logo.png