update extract_time_history() to use actual step times
update extract_time_history() to use actual step times

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