Add option to use RAW LUC emissions from MAgPIE in coupling

[merfort]

Purpose of this PR

This PR allows to use the raw land-use change CO2 emissions variable Emissions|CO2|Land RAW|+|Land-use Change in coupled runs instead of the smoothed variable Emissions|CO2|Land|+|Land-use Change, which is used by default. This can, in particular, be useful in runs with delayed start year. In such runs the smoothing algorithm of the LUC variable - a low pass filter to dampen spikes - overwrites values in the time step prior to the start year (see here). Using the raw LUC emissions prevents that, but comes at the cost of quite spiky emission profiles (see example below).

Type of change

• New feature
• Minor change (default scenarios show only small differences)
• 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 (NA)
• I adjusted forbiddenColumnNames in readCheckScenarioConfig.R in case the PR leads to deprecated switches (NA)
• 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:
  /p/tmp/merfort/REMIND_update_SMIP/remind

• Comparison of results (what changes by this PR?):
  A coupled NPi run with (default) smoothed LUC variable:
  /p/tmp/merfort/REMIND_update_SMIP/remind/compScen-rem-1-5_C_SSP2-NPi_smooth.pdf
  

A coupled NPi run with the raw LUC variable:
/p/tmp/merfort/REMIND_update_SMIP/remind/compScen-rem-1-5_C_SSP2-NPi_raw.pdf

[dklein-pik]

Looks good, thanks. The error messages in start_bundle_coupled.R and in getReportDate are identical at the moment. Could you phrase them differently so that the user knows from where they come? Thanks.

[merfort]

Looks good, thanks. The error messages in start_bundle_coupled.R and in getReportDate are identical at the moment. Could you phrase them differently so that the user knows from where they come? Thanks.

Good point! I changed them a bit.

[merfort]

Thanks a lot for the quick reviews!