prototype 0.1

it sort of works
there's a bit of a big but it's probably a rendering fail
but it might be a math fail

a/d moves player0 (bottom)
left/right moves player1 (top)

to simulate a touchscreen, the numbers will also move player1

known problems:
- ball bounces off air near paddle sometimes
- walls are calculated wrongly (i think this is a rendering fail though)
- java screen size 500x500 is not really 500x500