update Field: new n_components, val_shape attributes, new H1Mixin
update Field: new n_components, val_shape attributes, new H1Mixin

- new H1Mixin._setup_shape(), update Field.__init__()
- update Field docstring

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