update ScipyIterative solver to allow preconditioning
update ScipyIterative solver to allow preconditioning

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