Previously, the matrix was always assembled using a P1-basis, even if we used
it to measure errors of vectors pertaining to P2 or other spaces.  Nobody noticed
this, because the h1SemiNorm routine would not fail if the vector was larger
than the matrix.   Sigh...

[[Imported from SVN: r9770]]

That makes for slightly simpler code.

[[Imported from SVN: r9768]]

[[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: r9751]]

[[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]]