Coupling LandModel with full surface energy balance to SpeedyWeather

[bgroenks96]

This PR updates the old SpeedyWeather script for the PrimitiveDryModel air-soil temperature coupling and adds a new script with prototype coupling to a PrimitiveWetModel via the full SEB.

In the process of implementing this, I am also fixing bugs in the surface energy/water flux calculations.

• The ground heat flux calculation was previously using an incorrect sign convention. It should be G = R_net + H_s + H_l corresponding to balance equation R_net + H_s + H_l - G = 0 with all fluxes positive upwards (towards the atmosphere).
• The soil moisture evaporation resistance factor code was broken (we should add more tests...)
• SoilMoistureResistanceFactor is now the default choice for BareGroundEvaporation.
• Default values for incoming shortwave and longwave radiation now match the standard values for the global energy balance

[bgroenks96]

@milankl Since @maximilian-gelbrecht is on vacation, it would be great if you could approve this PR.

[bgroenks96]

@maximilian-gelbrecht and @milankl I have verified that the coupled model runs for up to 1 month of simulated time without errors, though I did not check the output. This is without the Richard's equation soil hydrology since this currently has problems unless you reduce the step size to an unbearably small number (like <10 seconds). This is, to some extent, expected; Richards' equation really needs implicit timestepping to be efficient.

[milankl]

Just some comments from my side skimming through!!!

[maximilian-gelbrecht]

Do you want to merge this PR first, and then in a follow up adjust to Speedy 0.19, or still do that here? I am also happy to help with that adjustment.

[bgroenks96]

#114 already updates to Speedy v0.19