Update version to 1.6 dev

[aprokop]

Still struggle to figure out whether it should be 1.6 or 2.0.

[aprokop]

One thing is that we still have SameMajorVersion compatibility, and not AnyNewerVersion. Not sure whether we want to switch.

[Rombur]

Still struggle to figure out whether it should be 1.6 or 2.0.

We found out in deal.II that it's a lot easier to decide before the release to go from 1.6 to 2.0 than the other way around because downstream app may decide to differentiate their code on the major version as soon as we update the version to 2.0

One thing is that we still have SameMajorVersion compatibility, and not AnyNewerVersion. Not sure whether we want to switch.

We should use AnyNewerVersion and let the user decide what to do. SameMajorVersion is too restrictive.

[masterleinad]

We should use AnyNewerVersion and let the user decide what to do. SameMajorVersion is too restrictive.

I agree.

[aprokop]

Unrelated failures in distributed test (sporadic).