Feat/review

[sulheim]

Main improvements in this PR:

A couple of bug fixes, updated requirements.txt, and code for plotting growth yield on glucose and glutamate.

I hereby confirm that I have:

• [x] Tested my code with all requirements for running the model
• [x] Selected devel as a target branch (top left drop-down menu)
• [x] If needed, asked first in the Gitter chat room about this PR