Lab2

Here are my suggested edits to lab2. After talking to the TAs and students in the class, we decided that timing things was too complicated for a beginning lab (not to mention that it isn't part of this lab's objective), so we removed those problems. The plan is to include timing in the profiling lab.
I think it's a good idea to remove this code. It didn't really serve to teach anything to students, and they never used it again in the lab.