fix dw_jump term, use the (optional) material parameter as a multiplier
fix dw_jump term, use the (optional) material parameter as a multiplier

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