update Field.setup_dof_conns() for string dc_type
update Field.setup_dof_conns() for string dc_type

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