update SchurGeneralized for no active DOF indices at solver creation time
update SchurGeneralized for no active DOF indices at solver creation time

- update SchurComplement parameters initialization

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