Bronson fork

[bronsonweston]

This pull request includes the code and walkthrough for the nutrition algorithm, updates to Demeter and a a Nutrition Modelling Toolbox.

I hereby confirm that I have:

• [X ] Tested my code on my own machine
• [X ] Followed the guidelines in the Contributing Guide
• [X] Selected develop as a target branch (top left drop-down menu)

(Note: You may replace [ ] with [X] to check the box)