Fix FieldMatrix::rightmultiply()

This addresses an issue mentioned in #5 and additionally turns runtime checks into compile-time checks whenever possible.

See merge request !22
(cherry picked from commit 71e2e4b8)

Signed-off-by: Steffen Müthing <muething@dune-project.org>

(cherry picked from commit 3bef4991)
Signed-off-by: Carsten Gräser <graeser@dune-project.org>

With g++-4.4 I got the following errors:

fmatrix.hh:106: error: no type named ‘const_iterator’ in ‘class std::initializer_list<std::initializer_list<int> >’

Looking into the header there is indeed the const_iterator (demanded by the standard)
missing. Therefore I refactored the code to use std::copy_n and thus am omitting the iterator
type.

At the same time I made the actual copying safer for the case that the initializer_list
is of different size and people compile with -DNDEBUG. The assertion for the size is still
left in there. Remove the assert or the size computation at your discretion.

We simply return a reference to the internal memory instead of copying the object.
This should save some copying when using FieldVector/FieldMatrix with non-trivial
types.  Also, it fixes crashes I have experienced with the ADOL-C automatic
differentiation toolbox [0].

I hope that this patch doesn't have any nasty side effects.  I didn't see any
so far.  Comments for this patch had been requested in FS 1449, and there have
been no objections.

[0] I have contacted the ADOL-C maintainer about this and he said the crashes
are not really bugs in ADOL-C, but that it is simply very difficult to write
a good operator-overloading AD program that can handle operator K returning
values.

Elias pointed out that one of the constructors got lost when merging
with the recent HEAD. This commit adds the missing constructor.

kudos to Elias Pipping, for details see (FS #1166)
as the new Dune requirements are >= g++ 4.4 we are sure that initializer_list is available.

The default implementation of DenseMatrixAssigner replaces redundant
code in dense matrix constructors taking a primitive data type.

[DenseMatrix] Introduce DenseMatrixAssigner for initializing dense matrices from arbitrary right hand sides

In order to overcome the deficiencies of istl_assign_to_fmatrix() we
propose to always use a struct DenseMatrixAssigner for initializing a
dense matrix. This class can be specialized by users for any right hand
side to be used in an assignment.  The new mechanism can bei default
implemented using existing implementations of istl_assign_to_fmatrix()
as well.

The majority of developers favor individual headers for (emulation of) C++11
features over collecting them in a single header cxx11.hh. This patch
renames cxx11.hh to constexpr.hh and moves it into the subdirectory std.
This is the place most developers would like these headers in (see
http://users.dune-project.org/doodles/4).

As decided on the developer meeting in Aachen, we support (but do not
rely on) the C++11 keyword constexpr. This patch adds an m4-check for
constexpr and a header (cxx11.hh) defining a macro DUNE_CONSTEXPR either
as constexpr or empty (depending on the compiler support for it). It is
then used in FieldVector and FieldMatrix on size, rows, and cols.

With the exception of mpicollectivecommunication.hh
and propertymap.hh, which I didn't understand.

[[Imported from SVN: r6784]]

[[Imported from SVN: r6512]]

[[Imported from SVN: r6188]]

[[Imported from SVN: r6184]]

* factor out most of the FieldMatrix math methods

missing: several functions oculd not me moved, as they require som
		 kind of type promotion traits

[[Imported from SVN: r6181]]

[[Imported from SVN: r6166]]

vectors using different storage containers

[[Imported from SVN: r6128]]

[[Imported from SVN: r6065]]

[[Imported from SVN: r5928]]

methods.  Make the arguments template parameters as in the general case.

This fixes FS 745.  Please merge to the release branch.

[[Imported from SVN: r5912]]

* add a specialization of sqrt to fvmeta, this should fix the
  ambiguous sqrt(int)

merge to release

[[Imported from SVN: r5874]]

[[Imported from SVN: r5858]]

*Add const to *multiplyany()
*Implement *multiplyany() for FieldMatrix<k,1,1>
Thanks to Atgeirr Flø Rasmussen!

[[Imported from SVN: r5704]]

[[Imported from SVN: r5683]]

[[Imported from SVN: r5662]]

* hide specializations from doxygen
* use ROWS and SOLS instead of n and m for the FieldMatrix
* use conjugateComplex instead of fm_ck
* document istl_assign_to_fmatrix

[[Imported from SVN: r5659]]

  type
* make *norm* in fvector and fmatrix use this real type

[[Imported from SVN: r5656]]

* update Makefiles and configure

[[Imported from SVN: r5643]]

[[Imported from SVN: r5609]]

[[Imported from SVN: r5608]]

[[Imported from SVN: r5581]]

Note that the current implementation of the determinant is rather
subobtimal.  While it is rather efficient, it is neither the most
numerically stable way to compute the determinant, nor does it work
for integers.  But I think it is much better than no implementation at
all.

[[Imported from SVN: r5549]]

[[Imported from SVN: r5548]]

[[Imported from SVN: r5532]]

[[Imported from SVN: r5531]]

(using LAPACK for dim > 2)


[[Imported from SVN: r5516]]