[test][facet][1pnc] do not require UMFPack

See merge request !2100

[test][sequential] remove failing grid/solver combinations

See merge request !2099

[test][ff][ms] Use constant time step size

See merge request !2097

Fix/test saltwaterintrusion increase robustness

See merge request !2092

Cleanup/unused params

See merge request !2088

[kepsilon] Fix compiler warning complaining about const having no effect

See merge request !2089

[readme][changelog][license] correct typesetting of DuMux

See merge request !2086

[fix] Add virtual destructor to vtkoutputmodule base class

See merge request !2082

[cleanup][fluid][brineair] Remove assert in constexpr mapping function

Closes #879

See merge request !2081

[seqsolverbackend] Fix Dune::Hybrid::size deprecation warning

See merge request !2083

[changelog] Add template for 3.3

See merge request !2080

[readme] Fix build badge link

See merge request !2079

Fix tests that fail with minimal setup

Closes #871

See merge request !2051

[1pni][3pni][test] use ILU0 with BiCGSTAB for 1pni and 3pni tests to ensure convergence with minimal setup (no UMFPack)

The conduction tests without UMFPack used SSOR as coarse grid solver 
which did not converge as well and lead to different timestep sizes.

Needed to ensure convergence with minimal setup (no UMFPack) for
test_2p_incompressible_tpfa_oilwet. The coarse grid solver is changed to
SSOR when UMFPack is not available, which did not converge as well.

[changelog] add section on GridView property deprecation

See merge request !2076

Due to !1905

[readme] Update build badges

See merge request !2075

[examples][changelog] added new examples and ex. doc to changelog

See merge request !2073

[common][pdesolver] Fix Dune::Hybrid::size deprecation warning

Closes #872

See merge request !2066