mobile level select fix + bonus level

a tiny update! the game used to crash on mobile phones on the level select screen, but I raised a bug report with the the author of the engine I’m using and he fixed it – thank you auroriax!

there are still issues with mobile that I probably won’t be able to track down, but hopefully this update means the game will work for more people.

also, I added in a small bonus level for fun - scroll to the bottom of the level select to play it

-pancelor