the vectors

Moving all convergence check and output things to a class 'Iteration' that also
manages the InverseOperatorResult.

Merge branch 'improve-matrix-testing' into 'master'

See merge request [!282]

  [!282]: Nonecore/dune-istl/merge_requests/282

in order to get a `static constexpr` result, the method must be called via the type and not via `this`.

And test it.

In preparation of testing more matrix types

... and use it in bcrsmatrixtest.cc

Currently we are only testing whether these methods are implemented
and can be compiled.

Found by porting the unit test to the general vectortest.hh framework.

Rather than testing them manually.

This is possible now because we have IsNumber in dune-common.

This uncovers a bug in the method axpy, which is also fixed
in this patch.

... and use it to test the BCRSMatrix class.

Currently, the new test only tests the vector space operations
required of a dune-istl matrix.  More is to come in subsequent
patches.

Merge branch 'bugfix/silence-useless-warnings' into 'master'

See merge request [!281]

  [!281]: Nonecore/dune-istl/merge_requests/281

Merge branch 'feature/fix-novlpschwarz' into 'master'

See merge request [!280]

  [!280]: Nonecore/dune-istl/merge_requests/280

Merge branch 'feature/use-latexmk' into 'master'

See merge request [!275]

  [!275]: Nonecore/dune-istl/merge_requests/275

It caused problems with latexmk

Merge branch 'fix-warnings' into 'master'

See merge request [!277]

  [!277]: Nonecore/dune-istl/merge_requests/277

Merge branch 'feature/amg-memory-management' into 'master'

ref:core/dune-istl This branch is cleaning up the AMG memory management in
order to get rid of manual pointer juggling and thus improve maintainability.

See merge request [!274]

  [!274]: gitlab.dune-project.org/core/dune-istl/merge_requests/274

if on the initial AMG pre was called, it is currently it not necessary to
call pre on a copy of that AMG. This is a feature that is not required
by the Preconditioner interface and thus it nothing anybody can rely on.
We now don't copy the temporary data anymore.