Automatic sets in 56_ghg_policy and 60_bioenergy and update of GHG emission policies

[flohump]

Please fill following information
(Add additional info if you think its important and not covered by this Pull Request (PR)):

Purpose of this PR

• Automatic sets in 56_ghg_policy and 60_bioenergy and update of GHG emission policies.
• Automatic sets will make it much easier to update GHG price and bioenergy demand scenarios in mrcommons
• The GHG emission policies have been revised for better understanding and to avoid confusion. The default setting is renamed to "redd+natveg_nosoil", which is content-wise unchanged.

Performance loss/gain from current default behavior

• No test runs.

Type of change

• Bug fix (Change which fixes an issue).
• New feature (Change which adds functionality).
• Minor change (Change which does not modify core model code i.e., in /modules).
• Major change (fix or feature that would change current model behavior).

How Has This Been Tested?

• Runs using starting script which tests current defaults (using test_runs.R).
• Runs using starting script which successfully runs the same scenarios as in test_runs.R but with the changes from PR.
• (If applicable) Runs using different scenarios/mappings which are not the default (12 regions/c200 clusters).

Additions or Changes to default configuration (default.cfg):

Additions are the introduction of new model components in default config

Changes are deletion or updates to the existing model components in default config

• Realizations:
• Scenario switches:
• Scalars/Constants:
• Model interfaces:
• Others:

Checklist:

• Self-review of my own code.
• Compilation check (model starts without compilation errors).
• Added changes to CHANGELOG.md
• No hard coded numbers and cluster/country/region names.
• The code doesn't contain declared but unused parameters or variables.
• In-code comments added including documentation comments.
• Compiled and checked resulting documentation with goxygen::goxygen() for the new/updated parts.
• Changes to magpie4 R library for post processing of model output (ideally backward compatible).

Special comments/warnings

• Notes

[tscheypidi]

overall approach looks good to me, but code needs some streamlining:

you are re-using here code which is used to modify our core/sets.gms file. Instead of duplicating that code by copying it I would like to ask you to ousource that part into a function and call that function where needed. Doing so will ensure that bugfixes in that part will be deployed automatically to all places where it is used and the code will become easier readable.
From what I can see the function would require three inputs: the file to be modied, the set name and description, and the set elements.

[flohump]

Unfortunately, this is not possible because the sets cannot be written to sets.gms in sequence. All sets have to be written at once, otherwise only the last set written will be in the code. But I can move the .tmp function and the modification header into functions that are called from within .update_sets and .update_sets_bioen_ghgprice_scen. What do you suggest?

[flohump]

I added .set_modification and .set_formatting. If you have further suggestions for streamlining, just let me know.

[tscheypidi]

Why not write a function then which writes all sets at once? (set entries could be provided as a list of entries and the function would simply 1) write the header 2) loop through the sets and write them 3) write the footer)

[tscheypidi]

(the set mappings in core/sets.gms should also fit in this scheme if you treat each set mapping (e.g. CAZ . (AUS,CAN,HMD,NZL,SPM)) as single set element and put that paste-magic which is creating these mappings outside of that function)

[flohump]

Done. I hope this is fine now.