fix imperative_burgers_1D.py for unified surface/volume terms
fix imperative_burgers_1D.py for unified surface/volume terms

- use Term.new() in main()

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