update assemble_by_blocks() for Variables under Equations
update assemble_by_blocks() for Variables under Equations

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