Update MSL 3.2.3 for the 1.16.0 release

[casella]

​MSL 3.2.3 Build 4 was released on 4 June 2020. It contains several bug fixes that were back-ported from MSL 4.0.0 and should be used instead of the current 3.2.3 release.

@sjoelund.se, @adrpo, can you please make sure that:

• this version replaces the current one in all our repositories and references
• the reference files that are used in Jenkins (e.g. for ​this report) are updated to the ones contained in this ​GIT LFS repository.

Updating the reference files is essentail since the revised data set contains previously missing items and removed some questionable reference tracks that led to bogus verification failures, so this should substantially boost our verification count for MSL 3.2.3, which has been currently stuck to 380/424 for quite some time.

[casella]

MSL 3.2.3 was already updated to build 4, because we already take it from the maintenance branch HEAD.

The reference files for MSL 3.2.3 are now successfully uploaded, there are no missing references for successful simulations.

Verification is now 391/425. I will double-check and report on #5288.

[casella]

OK, it turns out there are still some models failing in MSL 3.2.3 beta.4 because ​PR#3291 was merged into 4.0.0 but not back-ported in MLS 3.2.3.

I'll check with Thomas and Dietmar why this happens and if possible add the content of that PR to the 3.2.3 maintenance branch, so we get them in the release.

[casella]

Whatever could be back-ported into 3.2.3 maintenance has been put there. We can now close this ticket.