Added Steam Achievements

Hi! To anybody who is reading this.

In this update we've integrated the game with Steam, added achievements (doh) and fixed some minor bugs. There are currently eleven achievements in the game, but if you have any ideas for easter eggs and/or new achievements, feel free to join our discord server and share them!

We are still working on the level editor, which will be released on Steam this month (hopefully). We're also planning to do some rebranding soon, so we'll probably change the name and logo of our studio.