Extend intersection tests for 1d3d

Closes #987

See merge request !2453

[variablesbackend] Generalize vector dofbackend

Closes #1014

See merge request !2564

[fixup][md] Fix parallel check in multidomain assembler

See merge request !2562

Remove general outflow bc type

Closes #972

See merge request !2552

[cleanup] Delete installdumux.sh

See merge request !2560

has been replaced by the Python script installdumux.py

[doc][doxygen] Reduce error log to what we had for release 3.3.

See merge request !2558

[test] Add test with nonoverlapping grid manager that cannot communicate

See merge request !2557

Fix richards local res

See merge request !2559

[doc][handbook] Change package name scrpage2 to newer version scrlayer-scrpage.

See merge request !2556

gasViscosisty-update-in-changelog

Closes #1007

See merge request !2554

Addresses issue #1007

[newton] Set default parameters directly

Closes #1003

See merge request !2551

Feature/water vapor viscosity

Closes #573

See merge request !2452

Gabi Seitz authored Sep 30, 2020 and Timo Koch committed Apr 05, 2021

with contributions of Holger and Bernd

The following test results had to be adapted:
test_md_boundary_darcy2p2c_stokes1p2c_horizontal
test_md_boundary_darcy2p2cni_stokes1p2cni_horizontal
test_2p1cni_steaminjection_waterwet_box
test_2p1cni_steaminjection_waterwet_tpfa
test_2p2cni_waterair_box
test_2p2cni_waterair_buoyancy_box
test_dec2p2c
test_multiphysics2p2c
test_1pncmin_box
test_3p3cni_kuevette_box
test_3p3cni_kuevette_tpfa
test_3pwateroil_sagd_box

Feature/cmakelists

Closes #1006

See merge request !2549

Cleanup/remove deprecated

Closes #1004

See merge request !2548