For example, I'll use this for finite-strain elasticity problems.

Some of this should be in dune-fufem and/or dune-pdelab, but for the time
being it's easier to have it here.

[[Imported from SVN: r9939]]

[[Imported from SVN: r9853]]

This does what we want both on one and on many processors.

[[Imported from SVN: r9707]]

Because the gradient is needed anyway when computing the Hesse matrix.
Not computing it separately a second time shaves off about 8% wall time
of each iteration.

[[Imported from SVN: r9555]]

[[Imported from SVN: r9392]]

[[Imported from SVN: r8199]]

[[Imported from SVN: r7837]]

[[Imported from SVN: r7611]]

and barycentric coordinates.  This is easy because we know the
number of element corners at compile time (I currently don't
see support for non-simplex elements at all).  This saves 
time, but not much: about 1%.

[[Imported from SVN: r7550]]

[[Imported from SVN: r6209]]

Compute the local corrections in local coordinates on the tangent bundle now, instead of using the embedding in the surrounding space

[[Imported from SVN: r5985]]

[[Imported from SVN: r5966]]

For this now the TangentVector class of S^n has only n components,
while the EmbeddedTangentVector class still has n+1.
The code around it needs to be fixed accordingly.

[[Imported from SVN: r5963]]

[[Imported from SVN: r5931]]

[[Imported from SVN: r5690]]

[[Imported from SVN: r4080]]

[[Imported from SVN: r4063]]

[[Imported from SVN: r4055]]

[[Imported from SVN: r4038]]

[[Imported from SVN: r4030]]

[[Imported from SVN: r4024]]