better pep8 compliance for py/

`pep8 --ignore=E251,E221,E501,E241 py/`

Ignored errors are:
* 241 is more than one space after `:`
* 501 is line too long (>=80)
* 221 spaces before operator
* 251 spaces around keyword param assignment =

These errors could be fixed with a big amount of work, the `dataformat/` struct definitions get way uglier then.

Although ignoring some of the errors, this is certainly better than before.
Next up one could use `pylint` to find unused variables, imports etcetc which were not fixed by this patch.