restructure and extent report on convergence/non-convergence

Created by: fschreyer

I changed the report on convergence/non-convergence in the nash postsolve.gms to be a bit more structured and added tax revenue deviations. Robert and Lavinia, please say whether this suits our needs or we need more. There are five possible convergence messages why it did not converge for now.

This how it looks like after every iteration:

For the whole thing, see section Convergence diagnostics in /p/tmp/schreyer/Modeling/REMIND_H12/TaxConv_Check/output/SSP2-Base_ConvReport_2020-10-08_15.01.13/full.lst.

Robert, I also removed one display p80_surplus before and other displays that double s.t. people directly get to this part if they search for p80_surplus or p80_repy from the bottom. I feel it can be a bit confusing when you search if there are different displays with that name. Please tell me if you still would like more things displayed.