Fix compatibility with older Excel versions and LibreOffice

This release addresses a compatibility issue. Thanks to Wajid Umar for reporting the problem.

v1.2 Correct resistance lookup for digestate

The earlier version used cattle slurry resistance for digestate because of how the MATCH() function worked.
This problem has been corrected here.
Thanks to Maria Berglund for identifying this problem (and a solution).

v1.0 First release

This release matches the description in the BioSystems Engineering paper to the best of our knowledge.