update PhysicalQPs.get_shape() - make ig optional, check shape compatibility
update PhysicalQPs.get_shape() - make ig optional, check shape compatibility

- also allow any raveled shape length >= 1

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