Preparation for python3 support.

Used 2to3 (2to3 --output-dir=python3-version/mycode -W -n
python2-version/mycode) and manual editing. Hints via pyCharm IDE.
Merge pull request #12 from mamrehn/python3-few-steps

Preparation for python3 support by mamrehn.
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Used 2to3 (2to3 --output-dir=python3-version/mycode -W -n
python2-version/mycode) and manual editing. Hints via pyCharm IDE.
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