[[Imported from SVN: r8553]]

This change makes the localgeodesicfefunction test fail again.
So there must be a bug in the corresponding non-finite-difference
code.  Looking at simplex cases confirms me in this opinion.
But I don't find the bug...

[[Imported from SVN: r8463]]

[[Imported from SVN: r8462]]

[[Imported from SVN: r8376]]

To compute the derivative you need the function value (see my paper).
Therefore, it is computed as the first thing in the evaluateDerivative
method.  However, frequently, the assembler also needs the function value,
and also computes it.  Hence the function value is computed twice.
Since computing the function values takes quite a bit of time
this patch removes that redundancy, at the price of a slightly
more complicated API: if you happen to know the correct function
value when calling evaluateDerivative, you can now hand over the
value.  Then evaluateDerivative uses that value instead of recomputing it.

Short measurements have shown a speed increase between 25% and 45%.

[[Imported from SVN: r8362]]

[[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: r8059]]

[[Imported from SVN: r8051]]

[[Imported from SVN: r8045]]

add method to get the i'th base coefficient of a localGfeFunction and implement this method for the RigidBodyMotion template specialization

[[Imported from SVN: r8031]]

[[Imported from SVN: r8002]]

[[Imported from SVN: r7999]]

Compiles, but is not tested yet.

[[Imported from SVN: r7997]]

[[Imported from SVN: r7961]]

[[Imported from SVN: r7959]]

Add an operator() with three arguments to grant access
to the individual entries.

[[Imported from SVN: r7934]]

[[Imported from SVN: r7925]]

[[Imported from SVN: r7913]]

[[Imported from SVN: r7906]]

[[Imported from SVN: r7905]]

[[Imported from SVN: r7898]]

[[Imported from SVN: r7886]]

simplify the code by making the AverageDistanceAssembler accept the interpolation weights in a std::vector of FieldVectors

[[Imported from SVN: r7885]]

[[Imported from SVN: r7848]]

[[Imported from SVN: r7847]]

[[Imported from SVN: r7842]]

[[Imported from SVN: r7838]]

[[Imported from SVN: r7837]]

[[Imported from SVN: r7617]]

[[Imported from SVN: r7611]]

[[Imported from SVN: r7553]]

That space is a product space, and its LocalGeodesicFEFunction can be
implemented much more efficiently than the generic method.

[[Imported from SVN: r7551]]

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: r7548]]

[[Imported from SVN: r7547]]

[[Imported from SVN: r7412]]

Solve the minimization problems for the evaluation of gfe functions really down to machine precision.  This appears to make the overall algorithm much more stable

[[Imported from SVN: r7355]]

[[Imported from SVN: r7346]]

[[Imported from SVN: r7345]]