Lab Manual Update

I printed some of the pages that contained graphs to make sure they will come out OK on paper.  I have to adjust some gridlines for all of them (added tick lines) to make them easier to interpret.

I also wrote up instructions to use excel as an alternative to hand plotting for lab 4.5.

I als integrated some of Rob's revisions for 7.2-7.3.

I also worked on the volume reading exercise using pictures of real gc's with liquids.