Smarter collision handling. Zombie speed ratio = 4.5. Distance to edge
Throwables, not center. Respawn Humans when they die. Zombie pushes
Human away. Ignore collisions with invisible objects. Bullets dont stop
Zombie moving. Fixed top collisions for Throwables. Zombie carrying a
ThrowableObject is not limited in jump height.
No objects on roof in lvl1.

Merge branch 'master' of
https://github.com/vweevers/the-amazing-zombie.git

Conflicts:
	src/com/android/zombiegame/levels/Level.java
	src/com/android/zombiegame/levels/Level1.java
	src/com/android/zombiegame/levels/Level2.java