CO2 Emission Reduction Constraint

[Antti-L]

I just tested the constraint with the Example4 demo database, using IE=5 for the UC_RHSRT, and it worked fine.  The solution had normal completion with optimal status.  And I also checked the constraint formulation, which was correct.  So, it worked as expected.

And of course, the results also showed the emissions decreasing according to the constraint.