This effectively means that we use another prolongation of the distance 
function on M into the surrounding space.  Since the prolongation does not
matter this patch should not change the algorithm behavior.  However, it
shaves off a few norm calculations and division.  I cannot really measure
any difference though.

A possible effect of this is that while all values should remain on the
manifold, they may start to 'drift away' due to numerical artifacts.
So we may have to add an occasional renormalization step eventually.

[[Imported from SVN: r9558]]

Patrizio told me on the phone today that this is the way it should be.

[[Imported from SVN: r9557]]

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: r9554]]

[[Imported from SVN: r9553]]

[[Imported from SVN: r9552]]

[[Imported from SVN: r9551]]

[[Imported from SVN: r9550]]

[[Imported from SVN: r9549]]

[[Imported from SVN: r9548]]

[[Imported from SVN: r9547]]

[[Imported from SVN: r9546]]

[[Imported from SVN: r9545]]

[[Imported from SVN: r9539]]

[[Imported from SVN: r9535]]

[[Imported from SVN: r9534]]

[[Imported from SVN: r9533]]

[[Imported from SVN: r9532]]

[[Imported from SVN: r9526]]

[[Imported from SVN: r9525]]

and move from GenericReferenceElement to ReferenceElement

[[Imported from SVN: r9524]]

The Weingarten map is block-diagonal for a product space.

[[Imported from SVN: r9517]]

It used to be a compile-term error, but now that we have ADOL-C support
the missing gradient is not a problem anymore.

[[Imported from SVN: r9516]]

[[Imported from SVN: r9510]]

[[Imported from SVN: r9509]]

[[Imported from SVN: r9508]]

This patch brings it back.

[[Imported from SVN: r9477]]

[[Imported from SVN: r9476]]

[[Imported from SVN: r9475]]

[[Imported from SVN: r9467]]

[[Imported from SVN: r9466]]

[[Imported from SVN: r9453]]

[[Imported from SVN: r9452]]

[[Imported from SVN: r9451]]

[[Imported from SVN: r9450]]

[[Imported from SVN: r9449]]

[[Imported from SVN: r9448]]

I can't make up my mind whether I want 'ctype' or 'field_type'

[[Imported from SVN: r9447]]

ADOL-C doesn't play nice with OpenMP.  Hence we have to disable
the latter for the time being.

[[Imported from SVN: r9446]]

[[Imported from SVN: r9445]]