Processlib python3

The changes are needed to make processlib working with python 3.
Everything is still compatible with python 2.
Some testing have been done already with:
python 2.6.6, sip 4.9.3, numpy 1.6.2
python 2.7.6, sip 4.15.4, numpy 1.8.0
python 3.4.1, sip 4.15.4, numpy 1.8.0