Gabi Seitz authored Jan 29, 2020 and Timo Koch committed Jan 31, 2020

cornerpoint test is missing

* Use l in krw/krn instead of hard-coded l=0.5
* Correct the non-wetting relperm to comply with the Mualem model
* Correct the non-wetting relperm derivative

The parameter is used in the relative permeability curve in the Mualem model.
Mualem (1976) suggested that 0.5 is a good value for many soils. Sometimes a
value different from 0.5 is provided, which is why this patch implements it as additional variable.

[bugfix] Komega and LowReKepsilon typetags for the ransnc tests were switched

See merge request !1849

Feature/cleanup parallel solvers

See merge request !1848

* use specializations of VectorCommDataHandle instead

* createIndexSetAndProjectForAMG -> createParallelIndexSet
* getExtendedMatrix -> extendMatrix

[cppstandard] Require C++17

Closes #654

See merge request !1824

[flux][upwind] Include paramGroup when getting the upwindWeight

Closes #809

See merge request !1846

[cleanup] use std::string::empty for better readability

See merge request !1844

Fix/issue 802 inconsistent param lookup

Closes #802

See merge request !1842

Feature/newton unit test

See merge request !1836

This has been forgotten in bug fix commit 61c2158e

[comm] Use new communication headers with Dune 2.7

See merge request !1835

Feature/improve beavers joseph

See merge request !1833