Feature/restructure fluxvarscache

See merge request !347

the lambdas are used to obtain the tensors related to a law, i.e. an
expression for a flux (advective, diffusive, conductive). We now introduce
a lambda factory that passes lambdas for the different physical processes.

The flux variables cache now inherits from caches defined in the different laws.
These also define a respective filler class that is called when updating the flux
variables caches. That enables us to define different caches for different laws.

Feature/return perm by reference from volvars

See merge request !337

for all ported models (1p, 1p2c, 2p, 2p2c, 2pnc, richards)

Feature/implement interior boundaries cc

See merge request !344

Fix the flux stencil for every method independent of the stencils used
in the different flux laws. The matrix entries have to be reserved for all
possible occuring stencils if the method has parameter or solution dependent
stencils, otherwise the matrix needs to be rebuild every time. This implements
this unified flux stencil for box, cc, ccmpfa.
Remove a lot of duplicate code.
Separate the physical laws from the dicretization stencil.

Dennis Gläser authored 8 years ago and Timo Koch committed 8 years ago

The interaction volumes have to be instantiated with a valid fvGeometry etc and
during assembly they only exist temporarily for the transmissibility calculations.
Interaction volumes can now not be instantiated and stored globally anymore, but, why
would one like to do that. If global flux var caching is enabled, then the transmissibilities
are stored over the whole simulation time. This is the main thing one wants from them.

Mixeddimension framework

See merge request !334

Feature/evaluate perm at scvf ip

See merge request !343

Feature/correct vel output networks

See merge request !338

[bugfix][tpfa] Correct tpfa scheme for gravity on

See merge request !339

[pointsources] change interface to more general one

See merge request !335

[implicit][localjac] simplify numeric epsilon interface and use template function for global jacobian update

See merge request !333