who said one can not use commit messages as a little diary.

Well .. lets try.
First, I used aloscjas pojo-nested-field-selector branch to do my stuff. I found that aljoscha made some stuff in a way I would not do it.
But after a few hours of working, I found that many things he did have to be the way he did them. On the other hand, there were parts I really liked (the integration of the Tuples and Pojos into the TypeInformation system). The advantage of my approach is the full nesting-capability.

To avoid more duplcate work, I tried using Aljoschas work (the starting point I've used already) to backport my good changes.
This commit is the result of starting to work on this.

I'm stopping here with the backporting approach. It seems to be harder then expected and the missing parts are probably easier in the other branch