[[Imported from SVN: r8409]]

implement the remaining curvature and bending terms for the energy gradient.  These are not working yet, though.

[[Imported from SVN: r8408]]

So far, the long form of the quadratic bending energy has been
implemented and tested, and it appears to do the right thing.

This is a snapshot commit.  The code remains out-commented until
it is finished.

[[Imported from SVN: r8403]]

[[Imported from SVN: r8364]]

we know the function value when calling evaluateDerivative.  So let's give that value to the method, to prevent it from recomputing it

[[Imported from SVN: r8363]]

Use the long form for the quadratic energy stiffness.  I tested it: when kappa=1 is does the same as the short form

[[Imported from SVN: r8308]]

[[Imported from SVN: r8307]]

to set the shear correction factor.

[[Imported from SVN: r8290]]

[[Imported from SVN: r8182]]

target space classes.  In particular, the coordinate type
now has to be given explicitly.

[[Imported from SVN: r8149]]

[[Imported from SVN: r8024]]

[[Imported from SVN: r8023]]

[[Imported from SVN: r7923]]

[[Imported from SVN: r7888]]

[[Imported from SVN: r7887]]

[[Imported from SVN: r7868]]

[[Imported from SVN: r7867]]

[[Imported from SVN: r7842]]

[[Imported from SVN: r7611]]

[[Imported from SVN: r7567]]

[[Imported from SVN: r7566]]

coordinates into a separate method, and fix an index bug on the way.
Now this derivative passes an fd check.

[[Imported from SVN: r7565]]

[[Imported from SVN: r7564]]

[[Imported from SVN: r7560]]

[[Imported from SVN: r7559]]

[[Imported from SVN: r7558]]

[[Imported from SVN: r7557]]

[[Imported from SVN: r7556]]

[[Imported from SVN: r7555]]

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: r7543]]

[[Imported from SVN: r7423]]

remove the TargetSpace parameter of the Cosserat energy class -- Cosserat materials only make sense with RigidBodyMotion values

[[Imported from SVN: r7418]]

It will implement the energy of the elastic Cosserat modell
for continua and shells proposed by Patrizio Neff.  So far
it is only a copy of the harmonic energy, though.

[[Imported from SVN: r7417]]