[grid.walker.wrapper] use correct types

If the types are not extracted from BaseType the wrappers fail for dune-fem
GridParts.
[common.ranges] add support for dune-fems grid parts

This commit allows to call entityRange() for a either a grid view or a grid
part. In addition I renamed ViewRange -> EntityRange and
viewRange() -> entityRange() which is consistent with the existing
intersectionRange() and cornerRange()...
update viewRange() -> entityRange()
whitespace