update engine.py to comply pep8
update engine.py to comply pep8

rc/sfepy,lokik/sfepy,BubuLK/sfepy,sfepy/sfepy,rc/sfepy,sfepy/sfepy,vlukes/sfepy,vlukes/sfepy,sfepy/sfepy,BubuLK/sfepy,vlukes/sfepy,lokik/sfepy,rc/sfepy,lokik/sfepy,BubuLK/sfepy,lokik/sfepy