Grassland management implementation

[mppalves]

🐦 Purpose of this PR 🐦

This pull request implements a new realization of module 31_past that allows the separation of grass biomass production into areas of managed pastures and rangelands. It also updates module 13_tc adding a new set that distinguishes tau that is applied to managed pastures vs tau applied to crops.

🔧 Checklist for PR creator 🔧

• Labeling pull request correctly from the label list.

• Low risk : Simple bugfixes (missing files, updated documentation, typos) or Start/output scripts
• Medium risk : New realization / Changes to existing realization / Other changes which don't modify default.cfg
• High risk : New input files (if cfg$input is changed in default.cfg) / Modification to core model (eg. changes in equations, calculations, introduction of new sets etc.) / Other changes in default.cfg

• Providing additional information based on PR label

• Low risk : No new model run needed.
• Medium risk : Default run based on the current version of the fork from which PR is made
• High risk
  • Default run from the current develop branch
    default_dev_mar22
  • Default run based on the current version of the fork from which PR is made
    default_new_mar22 - New default
    IPSL-CM6A-LR-SSP2-set18 - New Realization ON

• 📉 Performance loss/gain from current default behavior 📈

  • Current develop branch default : 30.7 mins
  • This PR's default : 32.0 mins

• Added changes to CHANGELOG.md

• Compilation check (model starts without compilation errors - use gams main.gms action=c in model folder for testing).

• No hard coded numbers and cluster/country/region names.

• The new code doesn't contain declared but unused parameters or variables.

• Where relevant, In-code comments added including documentation comments.

• Made sure that documentation created with goxygen is okay (use goxygen::goxygen() for testing).

• Changes to magpie4 R library for post processing of model output (ideally backward compatible).

• Self-review of my own code.

• For high risk runs: validation of major model indicators - Land-use, emissions, food prices, Tau.

=======================================================================

**Below find the results comparing the current default and the new implementation: **

The blue line is the current develop (old TC module and old pasture module)
The red line is the new proposed default (new TC module and old pasture module)
The green line is the new implementation (new TC and new pasture modules)

⚠️ Additional notes or warnings ⚠️

NA

🚨 Checklist for RSE reviewer 🚨

• PR is labeled correctly.
• CHANGELOG is updated correctly
• No hard coded numbers and cluster/country/region names.
• No unnecessary increase in module interfaces
• All required updates in interfaces (if any) have been properly adressed in the module contracts
• In-code comments and documentation comments are satisfactory.
• model behavior/performance is satisfactory.
• Requested changes (if any) were applied correctly

🚨 Checklist for MAgPIE reviewer 🚨

• PR is labeled correctly.
• CHANGELOG is updated correctly
• No hard coded numbers and cluster/country/region names.
• Changes to the model are scientifically sound
• In-code comments and documentation comments are satisfactory.
• model behavior/performance is satisfactory.
• Requested changes (if any) were applied correctly

[tscheypidi]

looks quite good now. Just one additional suggestion for further simplification and two questions concerning some mz-files which are now being copied to the modules

[weindl]

Looks good!