update evaluate_at() to be more robust for tensor product elements
update evaluate_at() to be more robust for tensor product elements

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