Proposal of convergence tests using temperature and net radiative flux change at the TOA.

[diegojco]

Added convergence test in terms of the temperature and the net radiative flux at the TOA. Additions on file core.py

1) Added class attributes initialised to None: delta2, deltaT and deltaN (lines 180,181).

2) Added the test for the net radiative flux at the TOA in the class method is_converged().

The model only converges if both the temperature and net radiative flux at TOA fulfill their convergence criteria.

3) Added calculation of the old net radiative flux at the TOA (lines 278-291).

4) Added a calculation of a specific convergence threshold for the net radiative flux at the TOA (lines 379-383).

5) Added calculation of the net radiative flux change at the TOA (lines 385-396).

6) Added logger entries to check the status of the temperature and the net radiative flux changes (lines 397-403).

[lkluft]

Thanks for the PR! I will review it in the next few days ;)

[diegojco]

I will close this pull request. I found out that there are some of experiments that will never reach convergence because they oscillate. I need to correct this.