Leontief

Here are my edits to the leontief lab. Hopefully they have improved it somewhat.
It still lacks solutions and I'm out of time to add them right now.
It is still a relatively short lab.
I implemented Dr. Humpherys' suggestions and Dr. Jarvis' suggestions with the exception of using genfromtxt to have them read in the data.
We can add that in later, but I'm out of time for this lab at the moment.