For #41. Interface the Gameboard for MainPanel.

Require the Gameboard to have an updatePhysics() for MainThread.
Maybe not worthwhile; we'll see.
Coalesce objects from local and remote updates.
Begin JSON de/serialization.

Consider Jackson.
Forget JSON; use toString().

Jackson might cause even more GC.
Try to use basic strings to describe ourselves.
Add serialized Paddle,Ball,Brick for PhysicsCache.
Merge branch 'iss39multiplayer' of github.com:ko/breakout-island into iss39multiplayer

Conflicts:
	android/src/com/relurori/breakout/PhysicsLocalhost.java
	android/src/com/relurori/engine/physics/PhysicsCache.java