Update PyMCC3.py with Stauff's patch

Lefebvre, Robert Alexanderrequested to merge
mcc3-incompatibility into master

@nstauff please review this branch.

The steps I performed:

  1. Create a new branch from master
  2. Apply patch (copy and past REBUS branch's PyMCC3.py into this branch's PyMCC3.py)
  3. Create MR
  4. Push MR into the master
  5. If change is needed in the development branch, merge master into the development branch.

Merge request reports