Pipeline separation preview

[Stefan Dösinger]

> Looks good to me. You should probably start submitting it bit by bit,
> see if any regression come up, although it looks pretty safe to me.
Sure, that's the plan. I don't think submitting 50+ patches at once will
work well.

I have found 2 minor regressions, but fixed them already in my tree. (Mostly
incorrect calls in some state handler, like calling across pipeline parts
into a specific implementation of another pipeline part)