[[Imported from SVN: r7229]]

... instead of coordinates in the embedding space.  The usual problem
is that when working in the embedding space, a projection onto the
trust-region makes the iterate leave the tangent space.

[[Imported from SVN: r7035]]

[[Imported from SVN: r6673]]

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: r5548]]

[[Imported from SVN: r5534]]

[[Imported from SVN: r5528]]

[[Imported from SVN: r5347]]

[[Imported from SVN: r4138]]