* faceIndices start at numCellCenterEquations ( > 0)
* Accessing a Dune::FieldVector<int,1> with an index > 0 does not yield any
  error, warning, segfault etc.

* Changed probably due to correction of volume term for face

* Use correct faceVars

* To supress compiler warnings

* Convert matrix (if required) in newtoncontroller, as done in
  mixeddimension

* Do not use fixed values anymore

Improve Richards model - Add RichardsNC model

See merge request !360

[test][richardsnc] Add mass-conservation-output. Use heavy water tracer. Flow rate in kg/s instead of mol/s

The end point capillary pressure is the capillary pressure at sw=1.
For Brooks-Corey laws it is also called entry pressure.

The components are only in the water phase. The number of components
is statically extracted from the fluidsystem. Simply changing the
fluid system and boundary and initial conditions is sufficient to setup
a new model with n tracers.

* a main component and
* a conservative tracer component

Fix/2p2c elem sol

See merge request !384

mixeddimension-facetcoupling

See merge request !380