update plot_dofs.py for 1D
update plot_dofs.py for 1D

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