update Variable._set_kind() to always initialize .dof_name
update Variable._set_kind() to always initialize .dof_name

- use the variable name as the DOF name for parameter variables without a
  primary
- update ._setup_dofs()

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