This is what BCRSMatrix uses.

This makes the naming consistent again.

This is the name and semantics used by BCRSMatrix.
As BCCSMatrix is currently only used with scalar blocks
anyway, changing the meaning of the nonzeroes method
doesn't make a difference.

And add some more documentation.

It is nothing but a thin wrapper around a matrix.  This patch removes
the MatrixRowSet class and hands over matrices directly.  This
simplifies the code a bit.  More importantly, it paves the way
for setup of BCCSMatrix objects (needed by the SuiteSparse solvers)
from MultiTypeBlockMatrix objects.

The classes ColCompMatrix and ColCompMatrixInitializer were never
intended to be interface.  Let's make this explicit by including
them in the namespace Impl.  In fact, this patch moves them into
Dune::ISTL::Impl, to avoid potential name clashes with other modules.

This considerably reduces the amount of boiler-plate code.

Previously, the first template parameter was the matrix type that
the BCCSMatrix was a copy of.  Weird, and very closely tied to
the fact that BCCSMatrix/ColCompMatrix is currently only used
to get matrix data into SuiteSparse solvers.

This patch makes the first template parameter the type of
matrix entries.  This is what all other dune-istl matrices do,
and hence the code again gets easier to understand.

Remove operator= and setMatrix methods.  The code of these methods
is copied to all locations were operator= or setMatrix were
previously used.  This makes the calling code a bit longer,
but it simplifies the overall code structure considerably.

In particular, with these changes the BCCRSMatrix class does not
have 'virtual' methods anymore.

The file colcompmatrix.hh contains the rudimentary implementation
of a sparse matrix with scalar entries and column-compressed storage.
As part of cleaning up the UMFPackSolver implementation this patch
moves the matrix class into a separate file.  What's left in
colcompmatrix.hh is the matrix setup code.

The plan is to turn the matrix into something ressembling a real
dune-istl matrix.  That should make the code easier to understand,
and maybe something will even need compressed-column matrix
for other things one day!

Feature/scikit build

See merge request !412

make it possible to use setup.py without having an installed dune-common python package. This requires having the PYTHONPATH set as it is now done in dune-common/bin/dunepackaging.py

add missing mpi and parmetis flags to pamg tests

See merge request !408

add missing ParMETIS flags to pamg_comm_repart_test

See merge request !404

[ci] add configuration with DUNE_ISTL_WITH_CHECKING

Closes #72

See merge request core/dune-istl!403

[scalarproduct] Add constructor taking a shared_ptr<const Comm>

See merge request !383

Use modern CMake for FindSuperLU

See merge request !397

With SuperLU 5.0 version macros are provided.

Call find_path, find_library only one due to changed semantics
Drop undocumented SUPERLU_PREFIX and SUPERLU_ROOT, CMake uses
SuperLU_ROOT by default now.

make storeMatrixMarket able to choose the decimal precision

See merge request !400

Merge branch 'set_decimal_precision' of https://gitlab.dune-project.org/core/dune-istl into set_decimal_precision