Shatter bricks when they are hit by the ball.
Revert "Increase paddle springiness to compensate for saner physics."

The new physics have removed paddle/ball friction and totally broken
the game.

This reverts commit 5a16b20318a6d8f74871421da750ae0f6069f43b.
Revert "Improve physics a bit."

The new physics have removed paddle/ball friction and totally broken
the game.

This reverts commit af48a6a06ca622817df0073b90d404f0c013a4f9.