BLOM tag for NorESM2.3 release

[TomasTorsvik]

@matsbn , @jmaerz , @JorgSchwinger , @milicak
We should soon make a tag on BLOM for the upcoming NorESM2.3 release. I suggest we tag with v1.6.0, unless there is a reason for changing the major version to v2.0.0. Does anyone have an opinion what would trigger a new major version, or do we just continue incrementing the minor release number?

[JorgSchwinger]

Making hybrid coordinates the default would be a reason for v2.0.0, but we still don't do this?

[TomasTorsvik]

I agree that hybrid coordinates as default is a candidate for v2.0.0. We are not planning to make do this for NorESM2.3, but it is open for discussion for NorESM2.5.