Specialize std::tuple_size for MultiTypeBlock*

See merge request core/dune-istl!512

... because we also specialize `std::tuple_element` and
it derives from `std::tuple` after all.

[bugfix] Fixes implicit build mode of BCRSMatrix with zero rows.

See merge request core/dune-istl!510

Corner case that sometimes happens and produced a segmentation fault.

Remove all deprecated code

See merge request core/dune-istl!508

Rewrite CMakeLists for istl-solver-playground

See merge request core/dune-istl!507

Implement functions in SequentialInformation

See merge request core/dune-istl!494

[test] Add missing return in main

See merge request core/dune-istl!505

Unused variable warning indicated this oversight

Adapt changelog after release

See merge request core/dune-istl!504

Feature/pip install git master

See merge request core/dune-istl!503

Merge branch 'release29/license' into 'releases/2.9'

See merge request core/dune-istl!500

[bugfix] dune-common module version dependency.

See merge request core/dune-istl!501

update author list in license file

See merge request core/dune-istl!499

(cherry picked from commit 9108fc58ebbcf40305cb7ea1a8f28808b47adc16)

27471991 update author list in license file

[cleanup] Remove signed integer comparison warning.

See merge request !497

[cmake][python] Replace deprecated dune_python_install_package

See merge request core/dune-istl!488

add SPDX information

See merge request !490

dune.module: bump version to 2.10-git

See merge request !491

See https://reuse.software/ for a description.

Fixes segfault for least squares problems with SPQR

See merge request !489