Deprecate MAGICC6

[tonnrueter]

Purpose of this PR

Removes MAGICC6 based climate assessment from REMIND

Type of change

(Make sure to delete from the Type-of-change list the items not relevant to your PR)

• Bug fix
• Refactoring
• New feature
• Minor change (default scenarios show only small differences)
• Fundamental change
• This change requires a documentation update

Checklist:

• My code follows the coding etiquette
• I performed a self-review of my own code
• I explained my changes within the PR, particularly in hard-to-understand areas
• I checked that the in-code documentation is up-to-date
• I adjusted the reporting in remind2 where it was needed
• I adjusted forbiddenColumnNames in readCheckScenarioConfig.R in case the PR leads to deprecated switches
• All automated model tests pass (FAIL 0 in the output of make test)
• The changelog CHANGELOG.md has been updated correctly

Further information (optional):

• Test runs are here:
• Comparison of results (what changes by this PR?):

[tonnrueter]

Oh boy, this feels delicate...

I've never worked on the REMIND/GAMS core and I need y'all to please tell me how much this messes things up. It compiles and runs testOneRegi is all I can say:

• I have no idea how this will effect remind2
• There's still a plethora of references to the magicc6 realization of the 15_climate module in the scenario configs
• make test returns 2 failures:

Failure (test_01-codeCheck.R:13:3): GAMS code follows the coding etiquette
Failure (test_01-readCheckScenarioConfig.R:14:5): perform readCheckScenarioConfig with scenario_config_NGFS_v5.csv

The latter of which seems to be related to the scenario configs

[dklein-pik]

Does ./core/magicc.gms still exist?

[tonnrueter]

The core/magicc.gms file seems to have survived the purge 🤔 Thanks! I've removed it now

[dklein-pik]

Looks good to me.