Feature/move refelements element and quadratures to geometry

• The method 'domain' is at the moment removed from the entities's geometry (I might want to add it at a later point possibly on the entityhi)
• quadrature/referenceElements are not exported any more by the hierarchical grid module
• new method for obtaining the reference element and quadrature rule for given geometry type are added to dune.geometry
• added support for the quadpy packages (still experimental)

The is no downwards compatibility added. Things that need changing:

• entity.geometry.domain becomes dune.geometry.referenceElement(entity) (or entity.type).
• for p in aluView._module.quadratureRule(e.type, 2) becomes for p in dune.geometry.quadratureRule(e,2) (or (e.type,2)_.

This MR also adds

• support for quadpy but still experimental - especially the choice of the quadrature rule for the different geometry types needs to be improved.
• to integrate a function it is also possible now to write dune.geometry.quadratureRule(gt,order)(f) or when using quadpy dune.geometry.quadpy(gt, order, method)(f)
• there is a small demo in demo/testquad.py