And fix all spelling errors that codespell currently finds.

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

This is from an first prove-of-concept branch

It caused problems with latexmk

- create dedicated "eigenvalue solvers" group
- move implementation details into the "Impl" namespace
- minor cleanups of doxygen documentation

Remove stamp-vc file.

The information has been provided by the MatrixDimensions struct since roughly the end of 2010.
Correspondingly, the methods rowdim and coldim have been removed from the istl matrix implementations.
Apparently, we forgot to remove them from the Matrix class.

Fixes FS#FS#1649.

Reformat whole CMakeLists.txt file for better readability.

[[Imported from SVN: r1892]]

Previously communication.pdf was not in the tarball!

[[Imported from SVN: r1891]]

Otherwise the pdfs will not be installed from the tarballs.

.-- Diese und die folgenden Zeilen werden ignoriert --

_M   .
_M   doc/buildsystem/buildsystem.tex
_M   doc/doxygen/Doxystyle
_M   lib/dunemodules.lib
_M   COPYING
_M   bin/dunecontrol
_M   m4/parmetis.m4
_M   m4/cxx0x_nullptr.m4
M    cmake/modules/DuneDoxygen.cmake
_M   dune/common
_M   dune/common/geometrytype.hh
_M   dune/common/test/fmatrixtest.cc
_M   dune/common/densematrix.hh
_M   dune/common/shared_ptr.hh
_M   dune/common/genericiterator.hh
_M   dune/common/mpitraits.hh
_M   dune/common/parametertreeparser.hh

.-- Diese und die folgenden Zeilen werden ignoriert --

_M   .
M    doc/CMakeLists.txt
_M   dune/istl
_M   dune/istl/test/matrixredisttest.cc
_M   dune/istl/matrixutils.hh
_M   dune/istl/solvers.hh
_M   dune/istl/repartition.hh
_M   dune/istl/diagonalmatrix.hh
_M   dune/istl/supermatrix.hh
_M   dune/istl/paamg/smoother.hh
_M   dune/istl/paamg/parameters.hh
_M   dune/istl/paamg/hierarchy.hh

[[Imported from SVN: r1890]]

Otherwise the pdfs will not be installed from the tarballs.

[[Imported from SVN: r1888]]

[[Imported from SVN: r1887]]

[[Imported from SVN: r1867]]

[[Imported from SVN: r1866]]

[[Imported from SVN: r1859]]

[[Imported from SVN: r1787]]

Remove doc/comm as it is now part of dune-common Somehow the deletion of doc/comm got lost while resolving a tree conflict

[[Imported from SVN: r1785]]

[[Imported from SVN: r1783]]

The index sets themselves are already there.

Step 2: removing files from dune-istl

[[Imported from SVN: r1782]]

[[Imported from SVN: r1735]]

[[Imported from SVN: r1728]]

[[Imported from SVN: r1708]]

Check all programs even if MPI was not found. (similar to dune/common/test)
Fix poosc08_test to compile without MPI.

[[Imported from SVN: r1681]]

[[Imported from SVN: r1675]]

[[Imported from SVN: r1645]]