Add error to plots in 1D conv test
Add error to plots in 1D conv test

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