Breaking CMIP6 backward compatibility through bugfixes - iHAMOCC ready for NorESM2.1

[jmaerz]

This PR breaks CMIP6 backward compatibility since it introduces a few bugfixes to master:

• sediment alkalinity
• sinking of free dust with potential effects on burial rates
• burial time smoothing (time smoothing was formerly applied multiple times)
• OMP fixes (1D setup with iHAMOCC now reproducible also when OMP is switched on)

This PR makes master ready for the NorESM2.1 milestone (at least from the iHAMOCC point of view).

[jmaerz]

@mvertens, @JorgSchwinger and @TomasTorsvik : I suspect that we should briefly talk about the tagging during the BLOM core meeting tmw. Any opinion on this @JorgSchwinger? - see also discussion #295. Wrt the regression testing: I would be happy to incorporate the automated regression testing in my daily routine of coding (thus far mainly manually done). I hope that the full support will be available through the NorESM2.1 release. Wrt to specific testcases, I see that some combinations are probably needed - particularly in combination with the hybrid coordinates, at some point potentially with the new SI units, potentially a combination of HAMOCC logicals and potentially wrt to air-sea fluxes.

Wrt to merging #314 and #315, I'll wait a bit longer today for Tomas, but I suspect that he's busy with the workshop so that I merge the stuff in the afternoon.

[JorgSchwinger]

I don't have any strong opinion on the tagging-question. Using vX.Y.Z and updating z automatically sounds ok to me. But I'm fine with whatever is decided tomorrow (I can't make it)

[jmaerz]

@JorgSchwinger , ok, thanks for the input on the tagging. I suspect it will be a decision between Mats and Mariana then.

[jmaerz]

I performed another regression testing between an earlier stage of the feature-hamocc_beyond-CMIP6 branch and the latest stage that we will merge with this PR into master. It looked all good and we are all set for merging the PR, making master ready for the NorESM2.1.