Functions for MicroMap paper

[CCThinnes]

Added functions created for the MicroMap publication. Those functions build upon the metabolic cartography functions within the visualisation part of the COBRA Toolbox.

Please include a short description of enhancement here

I hereby confirm that I have:

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

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[farid-zare]

Hi Cyrille,
Thanks for your contribution.
I suggest to also add tests for these newly added functions to better track the updates and benchmark the results.
https://github.com/opencobra/cobratoolbox/blob/master/docs/source/guides/testTemplate.m