Minor edits as suggested by the students.
Merge pull request #334 from abefrandsen/student_edits

Student edits
Naming and spacing updates in leontief lab.
Grammar and spacing edits to leontieff lab.
Merge branch 'master' into leontief
Merge branch 'master' into leontief
Implemented Dr. Jarvis's suggestions for the Leontief lab.
Added the problem suggested by Dr. Humpherys to the Leontief lab.
Uncommented data-based problem in leontief lab.
Merge pull request #335 from insertinterestingnamehere/leontief

Leontief
Merge pull request #332 from abefrandsen/develop

Changes to recent labs in volume 1 (LU, Affine Transformations).