it's working!
Merge branch 'master' of https://github.com/Jianan-Li/Elevator

Conflicts:
	bin/.gitignore
	bin/Building.class
	bin/Rider.class
	bin/TestElevator.class
	output.txt
	src/Building.java
	src/Rider.java
	src/TestAll.java
	src/TestElevator.java
	src/TestEventBarrier.java