[[Imported from SVN: r9767]]

For a general grid, such loops are only possible for codimensions 0
and the grid dimension.

[[Imported from SVN: r9766]]

[[Imported from SVN: r9765]]

[[Imported from SVN: r9764]]

[[Imported from SVN: r9763]]

[[Imported from SVN: r9762]]

GlobalP2Mapper is intended to be for P2 finite element spaces, what
GlobalIndex is for P1 spaces: a numbering for all degrees of freedom
that is globally unique across all processors.

[[Imported from SVN: r9761]]

[[Imported from SVN: r9760]]

Iterators over entities are only mandatory for vertices and elements.
But here the user may also request indices for other entities.
Hence one cannot use a straight iterator.

[[Imported from SVN: r9759]]

No idea why valgrind didn't complain about this.

[[Imported from SVN: r9758]]

Even if there is only one processor.  Because even then the local
and global vectors differ in their ordering.

[[Imported from SVN: r9757]]

Currently only for quadrilaterals.  I'll implement triangles as soon
as I need them.

Unfortunately, VTK appears to only support 8-node quadrilaterals
(without an element dof).  So the element dofs get ignored currently.

[[Imported from SVN: r9756]]

With this patch we start to differentiate according the the function
space bases of the input data.  We write P1 data as is, and downsample
P2 and P3 data onto a P1 space.

[[Imported from SVN: r9755]]

[[Imported from SVN: r9754]]

This makes visualizing wrinkles much easier.

[[Imported from SVN: r9753]]

The CosseratStrain object is a 3x3 matrix, where the last column
is (0,0,1)^T.  This special structure allows to use specially tuned
matrix methods (e.g., the determinant), which I intent to do in the
future.

[[Imported from SVN: r9752]]

[[Imported from SVN: r9749]]

And use it in one place in VectorCommunicator

[[Imported from SVN: r9748]]

[[Imported from SVN: r9747]]

[[Imported from SVN: r9746]]

[[Imported from SVN: r9744]]

The Dirichlet nodes are handled directly via the ignoreNodes_ field.
I don't know how the matrix modification code ever got in here.

Removing the code doesn't seem to make any difference.  I find that
a bit surprising: I would expect multigrid and IPOpt to work better
if the matrix is truly symmetric.

[[Imported from SVN: r9742]]

Much easier to use than the previous API.

[[Imported from SVN: r9735]]

[[Imported from SVN: r9734]]

[[Imported from SVN: r9733]]

[[Imported from SVN: r9732]]

[[Imported from SVN: r9731]]

Those do many-to-one communication with a single method call.
Previously, two subsequent calls were needed.  There is no reason
why the interface has to consist of two calls.  A single one is
much easier to use.

[[Imported from SVN: r9730]]

[[Imported from SVN: r9729]]

After much back and forth: this is the correct way.  This size cannot
be taken from the transfer operators, because these operators exist
only if there is more than one level.

[[Imported from SVN: r9728]]

[[Imported from SVN: r9727]]

[[Imported from SVN: r9726]]

That works for fe spaces of all orders.

[[Imported from SVN: r9725]]

[[Imported from SVN: r9724]]

[[Imported from SVN: r9723]]

[[Imported from SVN: r9721]]

Christian Engwer told me a trick how to get the mpiHelper instance without
known argc and argv.

[[Imported from SVN: r9720]]

That way we can handle multigrid transfer matrices as well.

[[Imported from SVN: r9719]]

The globalindex.hh and uniqueentitypartition.hh is from Benedikt Oswald.
The rest is from Benjamin Bykowski, with a few fixes from me.

The globalindex stuff should go into dune-grid eventually, but it needs
some polishing first.

[[Imported from SVN: r9718]]

[[Imported from SVN: r9710]]