update UserMeshIO.read() for functions returning new mesh
update UserMeshIO.read() for functions returning new mesh

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