update version to 0.5.2
lots of pylint changes

There are still lots of warnings left.
Most of them "Redefining from outer scope".
The underlying problem is of course,
that we have too much code that is not in any function.
use list cromprehension, rather than filter/map

List comprehension is supposed to be easier to understand,
say pylint.
That is true for at least some of my constructs..