changed geometrygrid capabilities to be true for backup-restore only if coordfunction is default constructible

Merge branch 'use-No_Comm-tag-for-CollectiveCommunication' into 'master'

ref:core/dune-grid Using No_Comm means there is just one dummy communication
type instead of different types for different grids.

See merge request [!337]

  [!337]: gitlab.dune-project.org/core/dune-grid/merge_requests/337

Using `No_Comm` means there is just one dummy communication type
instead of different types for different grids.

Merge branch 'do-not-use-cubetopology' into 'master'

ref:core/dune-grid The new GeometryTypes interface is much nicer.

See merge request [!336]

  [!336]: gitlab.dune-project.org/core/dune-grid/merge_requests/336

The new GeometryTypes interface is much nicer.

Merge branch 'fix-typos' into 'master'

See merge request [!335]

  [!335]: Nonecore/dune-grid/merge_requests/335

Merge branch 'feature/yaspgrid-avoid-unused-variable' into 'master'

ref:core/dune-grid Whatever the mysterious meaning of the mysteryFactor is,
it's only used in the `#if HAVE_MPI` branch. Hence we should move it there to
avoid unused variable warnings.

See merge request [!330]

  [!330]: gitlab.dune-project.org/core/dune-grid/merge_requests/330

Merge branch 'fix-warnings' into 'master'

ref:core/dune-grid silences a compiler warning
\[-Winconsistent-missing-override\]

See merge request [!331]

  [!331]: gitlab.dune-project.org/core/dune-grid/merge_requests/331

silences a compiler warning [-Winconsistent-missing-override]

Merge branch 'document-vtk-writing-of-functions' into 'master'

ref:core/dune-grid

-   Describe object life-times of the method arguments
-   Mention in the change log that globally defined functions can now be
    written

See merge request [!329]

  [!329]: gitlab.dune-project.org/core/dune-grid/merge_requests/329

Whatever the mysterious meaning of the `mysteryFactor` is,
it's only used in the `#if HAVE_MPI` branch. Hence we should
move it there to avoid unused variable warnings.

Merge branch 'feature/distributed-boundary-segments' into 'master'

ref:core/dune-grid This MR implements a missing feature in the grid interface,
the possibility to distribute boundary segments during load balancing. This
create a problem, because grid readers such as GmshReader only read grid on
rank 0, and thus boundary segments only exist on that rank. So far there was
not possibility to re-distribute these segments leading to false boundary
projections in parallel computations. This MR implements this by providing a
BoundarySegmentBackupRestore class that allows to re-create a boundary segment
from a stringstream (char buffer). This requires the registry of a static
function that can restore the correct object from the stream. The factory is
necessary because of the type erasure when passing pointers of BoundarySegment
to the GridFactory. This also means a slight interface change for GmshReader.
The methods of GmshReader, such as GmshReader::read have to be called on all
ranks, because the correct BoundarySegment factory methods have to be
registered on all cores. As before reading is only done on core 0 which
already was checked in GmshReader before. The other implementation concerns
the DGF::ProjectionBlock where the boundary projections are now also
distributable.

Testing has been done with a corresponding branch on dune-alugrid.

See merge request [!325]

  [!325]: gitlab.dune-project.org/core/dune-grid/merge_requests/325

* Describe object life-times of the method arguments
* Mention in the change log that globally defined functions
  can now be written

Merge branch 'feature/implement-vtk-writing-of-c++-functions' into 'master'

ref:core/dune-grid Previously, only grid functions were supported.

See merge request [!327]

  [!327]: gitlab.dune-project.org/core/dune-grid/merge_requests/327

This namespace is almost empty and not used anywhere.
I think it ended up in the code by accident.

Previously, only grid functions were supported.

boundary segment objects. Also, restore returns unique_ptr instead of
raw pointer.

store class name for checking upon restore.

GmshReaderQuadraticBoundarySegment default implementation.

restore.

ProjectionBlock.

const Expression* to shared_ptr< Expression > to avoid memory leaks.

missing.

Merge branch 'use-std-make_unique' into 'master'

ref:core/dune-grid DUNE now requires C++14 which has std::make_unique.

See merge request [!323]

  [!323]: gitlab.dune-project.org/core/dune-grid/merge_requests/323

DUNE now requires C++14 which has `std::make_unique`.

Merge branch 'bugfix/make-skipping-of-test-loadbalancing-recognizable' into 'master'

ref:core/dune-grid This is used by dune-ctest as fallback if CMake is too old
to report skipped tests.

See merge request [!324]

  [!324]: gitlab.dune-project.org/core/dune-grid/merge_requests/324

This is used by dune-ctest as fallback if CMake is too old to report skipped
tests.

Merge branch 'fix/doc-gmsh-version' into 'master'

See merge request [!321]

  [!321]: Nonecore/dune-grid/merge_requests/321

Merge branch 'fix/bump-required-version-of-uggrid' into 'master'

See merge request [core/dune-grid!316]

  [core/dune-grid!316]: gitlab.dune-project.org/core/dune-grid/merge_requests/316

Merge branch 'ci/centralize-config' into 'master'

See merge request [core/dune-grid!317]

  [core/dune-grid!317]: Nonecore/dune-grid/merge_requests/317