Addition of home temperature to Biomee and P-model

[maloan]

EDIT Fabian: "From an earlier PR (that had been reverted and is now added in here):"

The functions calculating photosynthetic temperature responses (calc_ftemp_inst_vcmax and calc_ftemp_inst_jmax) have been updated following the equation 7 in Kumarathunge et al. (2019).
This implementation introduces a "home temperature" (tchome), defined as the long-term mean maximum temperature of the warmest month, which acts as a reference for acclimation.

Originally the home temperature (tc_home) was set to 25°C in the code for biomee related calculations. However, biomee related calculations also include the p-model (/src/gpp_biomee.mod.f90#L40), so the code was adjusted to also include tc_home calculated from the forcing in the run_biomee_f_bysite.R.

[fabern]

Now, we finally need to update the reference tests, as expected.
This makes sense. After all, this PR introduces:

• tc_home based on the meteo data

• AND switches to the Kumarathunge parametrisations of calc_ftemp_inst_vcmax() and calc_ftemp_inst_jmax()

• it remains to decide how the last test against rpmodel::rpmodel() should be fixed

  • we restrain comparison with rpmodel to vcmax and jmax and do not compare vcmax25 and jmax25 unless rpmodel is also updated with Kumarathunge parametrisations

[fabern]

@stineb and @maloan: this is now ready to be merged.
Given that it changes the model output of pmodel and BiomeE:
Could either of you please have a look and review this?

• Temperature sensitivity of vcmax and jmax are now computed with Kumarathunge (2019) instead of Kattge & Knorr (2007)
• tc_home is now internally computed and used for computation of temp-sensitivity of jmax.
• tc_growth, needed for vcmax and jmax, is now based on the dampened air temperature.

The changes due to this in the default simulations are negligible:
git show 1d590f8ca3a71c309e162a1b233a2c5af57f23ba
(best with a graphical git interface) tracks the changes in the results of the default simulations with the change in temperature-dependency in the model.

Once approved, I suggest we merge this with a standard merge commit.

[stineb]

All good. Thanks @maloan and @fabern