modified communicator

...not sure if it works...
meow
Merge branch 'master' of https://github.com/spham92/Nachos

Conflicts:
	nachos/threads/KThread$2.class
	nachos/threads/KThread$PingTest.class
	nachos/threads/KThread.class
	nachos/threads/KThread.java
	nachos/threads/Lock.class
	nachos/threads/PriorityScheduler$PriorityQueue$sortedQueue.class
	nachos/threads/PriorityScheduler$PriorityQueue.class
	nachos/threads/PriorityScheduler$ThreadState.class
	nachos/threads/PriorityScheduler.class
	nachos/threads/Semaphore.class