[box][maxwstefan] Remove unused local variables

See merge request !2014

(cherry picked from commit 44959489)

543afa9b [box][maxwstefan] Remove unused local variables

Merge branch 'cleanup/docu-handbook' into 'master'

See merge request !2011

update handbook for 3.2

See merge request !1901

(cherry picked from commit 32db16a9)

685278de [Handbook] add date in title page of handbook
ca3e2217 [Handbook] Add section on Backwards-compatibility
c26e125b [Handbook] change references from 3.1 to 3.2 and update dune versions
b901ef88 [Handbook] update section on restart with double precision
bca81cef [cleanup][Handbook] remove list of examples and add url to example list

This has been already fixed on master in !1971.

Merge branch 'fix/parameters-include' into 'master'

See merge request !1988

Merge branch 'feature/test-remove-python2' into 'master'

See merge request !2002

[test] Remove Python 2/3 compatibility

See merge request !2000

(cherry picked from commit 96267523)

4517ddb2 [test] Remove Python 2/3 compatibility

Merge branch 'feature/test-runtest-script-python3' into 'master'

See merge request !1999

[test] Update shebang to python3

See merge request !1998

(cherry picked from commit bc2e7c85)

e2c5e645 [test] Update shebang to python3

[common] Fix missing include in parameters

See merge request !1987

(cherry picked from commit 2a9a2dfe)

9b4c2f53 [common] Fix missing include in parameters

Merge branch 'fix/headercheck_3.2' into 'master'

See merge request !1972

[cleanup] fix headercheck errors

See merge request !1970

(cherry picked from commit edd81441)

c396f0c5 [cleanup] fix headercheck errors

Merge branch 'cleanup/doxygen_mainbranch' into 'master'

See merge request !1966

Cleanup doxygen

Closes #835

See merge request !1964

(cherry picked from commit 73cbb603)

8a37683f [doxygen] Temporarily remove copydoc and copydetails with file paths. Copydoc...
9064179e [doxygen] Correct copydocs without backslash.
1068eb21 [doxygen] Remove copydoc of something that does not exist.
7a26b0ff [doxygen] Fix link to parameterlist.txt.
06de8c79 [doxygen] Fix parameters which are not documented or do not exist.
2c465c69 Increase DOT_GRAPH_MAX_NODES. Default value of 50 is sometimes exceeded by Dumux.
de8d9f48 Use the doxygen command \deprecated nowhere. Deprecated stuff is already in...
c9c87ff0 [doxygen] Improve ingroups.
44a43db1 [docu] Correct dimWorld.
80aa104a [doxygen] Changes to stop things appearing as description of Dumux namespace.
ba332bb6 [doxygen] Add comment about nicer file names for the website.
ed560ce0 [doxygen][cleanup] We don't use the Dune depreaceted macro anymore

[sovler] Fix preprocessor guards in case UMFPack is not present

Closes #857

See merge request !1962

[diffusion] Do not store free diffusion coefficient in the volvars

Closes #828

See merge request !1959

[example] Use relative paths for example links on main page

See merge request !1963

[readme] Correct typesetting of DuMux

See merge request !1961

[fix] Correct forgotten linear solver calls

See merge request !1960

Feature/uzawa 3.2

See merge request !1921

* check matrix type, chose appropriate function (dune or dumux)
* MultiTypeBlock matrix only works sequnetially so far

[evalsolution] Use if constexpr

See merge request !1958

* TODO: overlapping?

[linear] Remove preconditionerBlockLevel

See merge request !1951