[backend/istl]
fix backend for general leaf nodes

up to now vector_descriptor_helper was specialized on LeafGridFunctionSpaceTag
we relaxed this and only check for tags derived from LeafGridFunctionSpaceTag
[gridfunctionspace] remove unnecessary include
[simpledofindex]
add missing hash support
Merge branch 'master' of http://git.dune-project.org/repositories/dune-pdelab
[lfsindexcache]
add typedefs for ContainerIndex and DOFIndex