[AMGBackend] fix AMGBackend for sequential grids and HAVE_MPI == 1

So far, the AMGBackend only worked for sequential grids if HAVE_MPI
was 0. This was due to the fact that AmgTraits distinguished between
parallel and sequential by evaluating HAVE_MPI. If HAVE_MPI was 1
but the Grid was sequential, this lead to compiler errors for the
constructor calls of the Communicator, LinearOperator and
ScalarProduct.

Do this properly now by using Dune::Capabilities for distinction
between the sequential and parallel case. For Dune 2.4, the
capability isParallel has to be used, while for Dune 3.0, it is
canCommunicate. The correct AmgTraits and constructor calls are
chosen by template specialization.

This solves FS#300.

See merge request !16

So far, the AMGBackend only worked for sequential grids if HAVE_MPI
was 0. This was due to the fact that AmgTraits distinguished between
parallel and sequential by evaluating HAVE_MPI. If HAVE_MPI was 1
but the Grid was sequential, this lead to compiler errors for the
constructor calls of the Communicator, LinearOperator and
ScalarProduct.

Do this properly now by using Dune::Capabilities for distinction
between the sequential and parallel case. For Dune 2.4, the
capability isParallel has to be used, while for Dune 3.0, it is
canCommunicate. The correct AmgTraits and constructor calls are
chosen by template specialization.

This solves FS#300.

Add fluidstate property for all implicit porous media models
if not yet defined

Conflicts:
	dumux/implicit/2pncmin/2pncminvolumevariables.hh

Feature/whitespace cleanup and hook

Bitte reviewen, asap, bitte.

See merge request !15

Now all tabs and trailing whitespaces are rejected in commits.
See FS#272 for more details.

The check was turned on for debug purposes and exited with an error
if the same parameter was read into object of different type. This
is not an error. For reading vectors it is even an important feature
that it's possible to read it into different types of containers
depending on the usage.

Reviewed by martins

[math] (Re-)implement cross product in 2d/3d

This makes the old cross-product more efficient. The old version
initialized a FieldVector with zeros and then filled it. The
new version builds it's directly using consise bracket notation.
The result can be moved without creating a copy.

Implement a cross product in 2d that returns a scalar.
Not mathematically clean but still useful.

2d and 3d cross products now explicitly only work in 2d and 3d.
Other dimensions will trigger a compiler error.

See merge request !14

Feature/externalscript

Unfortunately this contains some other commits which should have gone directly to master. I apologize for this mistake.

See merge request !12

This makes the old cross-product more efficient. The old version
initialized a FieldVector with zeros and then filled it. The
new version builds it's directly using consise bracket notation.
The result can be moved without creating a copy.

Implement a cross product in 2d that returns a scalar.
Not mathematically clean but still useful.

2d and 3d cross products now explicitly only work in 2d and 3d.
Other dimensions will trigger a compiler error.

[gnuplot] Do not set terminal as default

Gnuplot will pick a default terminal itself. If you
change the number of plotting windows a terminal has to be
specified. If not specified by the user the default is x11.

See merge request !13

Gnuplot will pick a default terminal itself. If you
change the number of plotting windows a terminal has to be
specified. If not specified by the user the default is x11.

[material,decoupled] add partial and vapor pressure functions

The convenience functions for partial pressure and vapor pressure are helpful for calculating the relative humidity.
There is now also a new function for setting the relative humidity instead of the mass or mole fractions. This makes life much easier, when working together with people from atmospheric science.

See merge request !11

[material] Introduce check if phase is gas, remove unused function in immiscible fluidstate, and cosmetic changes

Mobility output for decoupled models has been added.
Therefore, the corresponding reference files have changed.

Reviewed by Thomas

reviewed gruenich

The convenience functions for partial pressure and vapor pressure are helpful for calculating the relative humidity.
There is now also a new function for setting the relative humidity instead of the mass or mole fractions. This makes life much easier, when working together with people from atmospheric science.

Remove deprecated support for ALUGrid.

Use dune-ALUGrid instead.

See merge request !10

Use dune-ALUGrid instead.
(reviewed and improved by timok)

(reviewed by martinb)

TypeTag replaces GridView and Scalar as template arguments
boundaryTypes and neumann function with vertex as input are not needed
boundaryTypes and neumann function with globalPos as input are renamed into ..AtPos

(reviewed by martins)

Follow naming scheme from Dune and use index and subIndex instead.
(reviewed by martinb)

Feature/use range for

Whereever possible, replace all entity/intersection iterator loops by range-for-loops.

See merge request !9

In the LocalResiduals, there are several protected functions taking
an IntersectionIterator,
    void eval...(const IntersectionIterator &isIt,

In order to be callable with an (address of an) intersection, the
explicit requirement on the type IntersectionIterator has been
relaxed:
    template<class InetrsectionIterator>
    void eval...(const IntersectionIterator &isIt,

In a future steps these functions will be deprecated and replaced by
equivalents that take intersection objects.

Discussed with and approved by Christoph.

Calls like
  const auto& element = *gridView.template begin<0>();
result in element referencing a temporary. Use a copy instead:
  const auto element = *gridView.template begin<0>();