I still think they ought to go in the pybind11 files. But won't need nearly as many of them once we merge things into larger modules, because all of the intra-package dependencies will already be accounted for.

My understanding is that this cleanup pass is an intermediate stage: the final stage will be to mostly combined the small wrappers into larger wrappers. That is stated as the justification for not having pybind11 import statements in the wrappers. But I am not very happy about this. I would much have this code be correct, with the imports in place so that the modules are self-contained, as we expect them to be. That way we can take our time about the final cleanup pass.

But even if we do decide to go for a quick and dirty solution for imports, for now, something needs to be done because as far as I can see many imports packages are not being imported anywhere, not even the __init__.py files. This makes the code needlessly fragile.

I'll put this back into In Progress.

I added py::module::import statements for all cross package imports that were explicitly needed. Furthermore I changed all from __future__ import lines to the standard as requested.
Finally I verified the build on Jenkins and fixed some minor issues here and there.
Ready for second review.

Overall this looks great. Many of the packages can be merged with no changes. However, there are still a few missing imports in some packages and I found one or two other things.