Artstyle overhaul

The result of my last month of searches for a better artstyle are here! I've wanted to do this for a long time. I think the game is either already on its final look or very close to it. There's still some stuff to work on with UI, fonts and transitions for instance. But I'm very happy with the current looks. 

So far I've only lifted the looks of the first 9 levels, as the subsequent levels belong to other biomes and will need more art production. Now that the visual question is out of the way, I will go back to other aspects of the game and polish what needs polish still. As such, other biomes & new levels are not on my priority list. 

Enjoy playing the improved levels (and please point out any issues you notice, especially since I added parallax scrolling to the backgrounds).