History complete
Merge branch 'history' of github.com:tmzhuang/pvz-reloaded into history

Conflicts:
	src/pvz/GameModel.java
Merge branch 'master' of github.com:tmzhuang/pvz-reloaded

Conflicts:
	src/pvz/Level.java
Win-lose implementation

When all zombies level spawns are dead, loads next level, unless it is
the last level in which case a win message is printed and the game
exits. If any zombies reaches the end of a strip, a lose message is
printed and the game ends
Merge branch 'master' of github.com:tmzhuang/pvz-reloaded

Conflicts:
	src/pvz/Level.java
Merge branch 'win-lose'

Conflicts:
	src/pvz/Level.java