Some functions changed return type from python2 to python3

TODO: not everything is tested, a full review is needed + run is needed

flake8 --select W391,E302,E301,E304

autopep8 can't fix W391 even though it claims it can.
Fixed using a simple custom script.

python modernize.py --no-six -f libmodernize.fixes.fix_print -w

With manual fixes as the import was put always on top.

refs #803

Double new line at the beginning of the table