Introduce different methods for realize_input/output
realize_direct_input/output and setup_input/output. The setup methods cover
code generation outside the sumfact kernel function (creating input array or
accumulating result). realize and realize_direct handle the input/output in the
nonfastdg and fastdg code branch.

Seperate interface methods make it a lot easier to find out where each of those
methods will be applied. Besides that most interface classes need to provide
more that two of those methods anyway...

Non-fastdg: Permutation of the input happens before the sum factorization
kernel when we setup the input. This is done by a method of the corresponding
interface class.

Fastdg: In this case the input will always be ordered according to x,y,... This
means the permutation needs to happen in the sumfact kernel. Since we want to
vectorize sumfact kernels with different input permutation in an upper/lower
way we need to do this permutation in the corresponding interface class. This
is done in the realize_direct method and in the vectorized case the
corresponding methods of the scalar sumfact kernels are called.

So far only for fastdg. This should also happen in the non-fastdg case.

Note: They are not yet used but in the long term the permutation should be
handled here since it is about input/output setup.

Note:

- direct_is_possible true/false could probably be handled in an upper/lower
  vectorization way.

- Vectorization of SF kernels should be based on cost permuted matrix sequence.

Merge branch 'feature/project-renaming' into 'master'

See merge request [dominic/dune-perftool!283]

  [dominic/dune-perftool!283]: Nonedominic/dune-perftool/merge_requests/283

Hoperfully achieving more robustness w.r.t. submodule changes

Merge branch 'autotune-merge' into 'master'

ref:dominic/dune-perftool Resolving conflicts of [!270]

See merge request [dominic/dune-perftool!282]

  [!270]: gitlab.dune-project.org/NoneNone/merge_requests/270
  [dominic/dune-perftool!282]: gitlab.dune-project.org/dominic/dune-perftool/merge_requests/282

Merge branch 'feature/use-custom-geometry-transformation' into 'master'

ref:dominic/dune-perftool This computes the determinant and jacobian inverse
transposed directly within loopy and does not call the corresponding grid
functions. Using some simple precomputations this is faster if
number_of_blocks>=2.

This also allows straight forward vectorization for unstructured grids.

I don't know how the computation of the geometry transformation is done in the
sumfactored case, but maybe there is some overlap, which could be reduced.

See merge request [dominic/dune-perftool!276]

  [dominic/dune-perftool!276]: gitlab.dune-project.org/dominic/dune-perftool/merge_requests/276

Merge branch 'feature/skylake-single-precision-transposes' into 'master'

See merge request [dominic/dune-perftool!271]

  [dominic/dune-perftool!271]: Nonedominic/dune-perftool/merge_requests/271

Merge branch 'feature/matrix-inversion' into 'master'

ref:dominic/dune-perftool Matrix inversion at code generation time does only
work to a very limited extent (up to n=4). We can instead assemble the tensor
in C++ and invert it there (e.g. using Dune::FieldMatrix)

This fixes [#123].

Still TODO:

-   \[ \] Vectorized Inversion

See merge request [dominic/dune-perftool!263]

  [#123]: gitlab.dune-project.org/NoneNone/issues/123
  [dominic/dune-perftool!263]: gitlab.dune-project.org/dominic/dune-perftool/merge_requests/263


Closes #123