The last bits in dune-common were removed in dune-common!719.

Merge branch 'feature/require-cmake-3.13' into 'master'

See merge request [core/dune-istl!387]

  [core/dune-istl!387]: Nonecore/dune-istl/merge_requests/387

Merge branch 'feature/fix-broken-macro-guard' into 'master'

ref:core/dune-istl\> The loaction of the macro guard lead to the method test
not returning a value if neiter SUperLU nore SuiteSparse are found. While the
test is not executed in this case due to a CMake guard, these macro guards
should be placed in the correct place anyways for reasons of code hygiene.

See merge request [core/dune-istl!385]

  [core/dune-istl!385]: gitlab.dune-project.org/core/dune-istl/merge_requests/385

The loaction of the macro guard lead to the method `test`
not returning a value if neiter SUperLU nore SuiteSparse
are found. While the test is not executed in this case due
to a CMake guard, these macro guards should be placed
in the correct place anyways for reasons of code hygiene.

Merge branch 'feature/blocklevel-detection' into 'master'

ref:core/dune-istl\> Proposal for extending [!168] to MultiTypeBlockMatrix. As
the blockLevel for MultiTypeBlockMatrix is sometimes not uniquely determined
this proposed three functions minBlockLevel, maxBlockLevel and blockLevel. The
first two always work. The last one is only enabled if the first two return
equal levels. There is an additional function
`constexpr bool hasUniqueBlockLevel()` which checks this condition at compile
time.

Depends on the fix in hybrid utilities [dune-common!794]

See merge request [core/dune-istl!375]

  [!168]: gitlab.dune-project.org/NoneNone/merge_requests/168
  [dune-common!794]: gitlab.dune-project.org/Nonedune-common/merge_requests/794
  [core/dune-istl!375]: gitlab.dune-project.org/core/dune-istl/merge_requests/375

Merge branch 'feature/dont-require-fortran-for-arpack' into 'master'

ref:core/dune-istl\> dune-common does no longer require / look for Fortran, so
the condition would be always false.

See merge request [core/dune-istl!371]

  [core/dune-istl!371]: gitlab.dune-project.org/core/dune-istl/merge_requests/371

Based on the intial implementation by Oliver Sander (see !168)

dune-common does no longer require / look for Fortran,
so the condition would be always false.

Merge branch 'feature/cleanup_preconditioner_configs' into 'master'

ref:core/dune-istl\>

### Summary

This MR adds missing documentation for ParameterTree arguments and replaces
repeated constructors by delegating constructors.

See merge request [core/dune-istl!379]

  [core/dune-istl!379]: gitlab.dune-project.org/core/dune-istl/merge_requests/379

Merge branch 'issue/fcg_solver_constructor' into 'master'

ref:core/dune-istl\>

### Summary

Add missing constructor (with operator, precon, and parameter-tree) to
RestartedFCGSolver

### Details

The constructor with operator, precon, and parameter-tree, but without
scalar-product was just missing and is added by this MR for consistency with
all the other iterative solvers.

See merge request [core/dune-istl!378]

  [core/dune-istl!378]: gitlab.dune-project.org/core/dune-istl/merge_requests/378

Merge branch 'feature/direct_solver_constructors' into 'master'

ref:core/dune-istl\>

### Summary

Add ParameterTree constructors for direct solvers

### Details

To be consistent with other linear solvers, a constructor with a ParameterTree
argument is added to all direct solvers. Mostly the verbosity level is read
from the configuration, but SuperLU also reads the *reuseVector* parameter.

See merge request [core/dune-istl!377]

  [core/dune-istl!377]: gitlab.dune-project.org/core/dune-istl/merge_requests/377

Merge branch 'feature/replace-ifelse' into 'master'

See merge request [core/dune-istl!376]

  [core/dune-istl!376]: Nonecore/dune-istl/merge_requests/376

Merge branch 'bugfix/MissingAppend' into 'master'

See merge request [core/dune-istl!374]

  [core/dune-istl!374]: Nonecore/dune-istl/merge_requests/374

Merge branch 'explain-implicit-buildmode' into 'master'

ref:core/dune-istl\> Circumstances forced me to finally learn what the
BCRSMatrix 'implicit' build mode really does, and where its limitations come
from. I had to read the code for that. As it turns out, the documentation of
the mode is quite misleading. My main gripe is that the code uses two
different auxiliary data structures, but the documentation calls them both
'overflow'. This problem even extends to the variable naming in the code.
Behold: the parameter 'overflowsize' is NOT the size of the member 'overflow'.
It doesn't even have anything to do with that member\...

To improve the situation, this patch does three things:

1.  It rewrites the documentation. In particular, the 'overflow area' is now
    clearly distinguished from the 'compression buffer'. The latter is a new
    word I introduce.

2.  It renames the BCRSMatrix method parameter _overflowsize to
    compressionBufferSize, because that is what it is: That parameter has
    nothing to do with the 'overflow' data member, or even the concept of
    'overflowing' in general.

3.  It renames the exception 'ImplicitModeOverflowExhausted' to
    'ImplicitModeCompressionBufferExhausted', for the same reason. This is the
    only interface changes. The code keeps the old exception for
    backward-compatibility, but makes it trigger a deprecation warning.

See merge request [core/dune-istl!370]

  [core/dune-istl!370]: gitlab.dune-project.org/core/dune-istl/merge_requests/370

Merge branch 'fix/non-mpi-build' into 'master'

ref:core/dune-istl\> When MPI is not available or explicitly disabled with the
CMake build option -DCMAKE_IDSABLE_FIND_PACKAGE_MPI=TRUE, some tests were
unable to build. I've either fixed or disabled those tests (for those tests
that were testing MPI-only features).

I've also fixed overlappingschawarztest, which did not build when SuperLU was
not found.

The commit concerning MPI should probably be backported to the releases/2.7
branch, as it is affected by the same build failures. The fix for
overlappingschwarztest only appeared after commit
05f80ffa which fixed a bug which previously
disabled the test. Since this commit is not on the releases/2.7 branch, there
is probably no need to backport my fix for overlappingschwarztest.

See merge request [core/dune-istl!372]

  [core/dune-istl!372]: gitlab.dune-project.org/core/dune-istl/merge_requests/372

This test should not be necessary anymore, since commit
05f80ffa fixed the CMAKE_GUARD argument
for this test, so that it is not compiled anymore if either UMFPACK or
SuperLU are missing.

That line had to be removed as it did not compile if either UMFPACK or
SuperLU were missing. For example while I had UMFPACK installed but not
SuperLU, gcc gave me the following error message for the removed line:

…/dune/istl/test/overlappingschwarztest.cc:260:17: error: ‘HAVE_SUPERLU’ was not declared in this scope

Merge branch 'feature/addPythonBindings' into 'master'

See merge request [core/dune-istl!369]

  [core/dune-istl!369]: Nonecore/dune-istl/merge_requests/369

When MPI is not available or explicitly disabled with the CMake build
option -DCMAKE_IDSABLE_FIND_PACKAGE_MPI=TRUE, some tests were unable to
build.

The tests created from solverfactorytest.cc.in and part of
scalarproductstest.cc use Dune::OwnerOverlapCopyCommunication which is
defined behind `#if HAVE_MPI` and is thus not available in a non-MPI
build. I've thus disabled those tests when MPI is unavailable.

The matrixmarkettest did not work without MPI, as it contained some code
using the wrong template parameters when HAVE_MPI was not set. Those
template paramters have been fixed now.

I've confirmed, that after my changes `make build_tests` succeeds to
build all tests and that those tests run without failure.