[DOFMapper] Port DOFMapper from GeometryType and map to GeometryTypeIndex and vector
[LocalAssembler] Clean up apply TMP
[MultiDomainGridFunctionSpace] Port to new PDELab DOF and backend API
[CouplingGridFunctionSpace] Port scalar coupling spaces to new PDELab DOF / backend API
[DOFIndex] Fix incomplete transition from MultiIndex to DOFIndex

- Construct DOFIndex in gfs_to_coupling_lfs
- Consequently use DOFIndex instead of MultiIndex in transformation descriptors
[MultiDomainLFS] Fix naming BackendType -> Backend
[GridOperator] Remove deprecated nested helper struct MatrixContainer
[GridOperator] Add constructor argument for matrix backend instance
[LocalAssembler] Adapt to new way of obtaining matrix pattern type
[LocalFunctionSpace] Remove deprecated references to MultiIndex and global_storage
[MultiDomainLocalFunctionSpace] Make sure FillIndicesVisitor TMP has access to internal state
[interpolate] Simplify implementation of setTime() dispatch across descriptor elements using new TypeTree functionality
[interpolate] Port interpolation to new PDELab API
[MultiDomainGridFunctionSpace] Provide shorter 'GridView' typedef
[DataWrappers] Rename lfs* wrappers to lfs*_cache

As the new PDELab infrastructure exposes LFS Caches instead of the spaces
themselves, this patch renames the wrappers to clearly show the change.

Moreover, the patch removes the suffix-less wrapper (e.g. wrap_lfsu()). Use
wrap_lfsu_s_cache() instead for improved consistency.
[GlobalAssembler] Fix typo causing nasty bug
Merge branch 'master' into HEAD

* master:
  [DataWrappers] Move macro definitions for creating data wrappers to datawrappers.hh
  [GlobalAssembler] Fix typo causing nasty bug
[SubProblemLFS] Update to new PDELab API

- We now have DOFIndices instead of global indices
- Implement new method insert_constraints()
[Utilities] Port SubProblemLFS construction helpers to new, LFSCache-based API
[ISTLBackend] Add new file istlhelpers.hh with specialization of extract_istl_vector_helper for CouplingGridFunctionSpace