Shaders? More like Hades!

FINALLY I have managed to fix the font shader! It turns out it's a know broken thing. Well, not broken, so much as a quirk of how fonts are handled. But after much digging and experimenting I have finally worked out the magic sauce: use screen coordinates coupled with lots of math to get it right. And right it is, now.

Oh, and you can now play any level you like direct from the main menu.