Calling log(a,b) returned a-b instead of b-a.

Also, enable unit tests for the RealTuple class.  The current test
will not trigger the bug in the log method: that will come shortly.

Finally, this commit is the first that mentions its user-facing
changes in the newly introduced CHANGELOG.md file.

Previously, the actual projection happened by calling the constructor
of one of the classes that implements points on a manifold.  This patch
introduces an new method projectOnto, which makes the projection more
explicit.

Needed for gradient-flow applications.

Solvers from dune-solvers expect the number type to be exported
as field_type.  This patch adds the missing export to RealTuple.

[[Imported from SVN: r9866]]

[[Imported from SVN: r9845]]

[[Imported from SVN: r9588]]

When using the classes with ADOL-C, T becomes an 'adouble',
which is a non-trivial type.  However, the convexityField
is constexpr (and with a reason -- otherwise we could write
the initialization together with the declaration), and
constexpr and non-trivial types don't work together.

[[Imported from SVN: r9444]]

This is needed to use the ADOL-C automatic differentiation library.

[[Imported from SVN: r9398]]

[[Imported from SVN: r9397]]

[[Imported from SVN: r9196]]

And use it in the test.

This patch uses the new 'constexpr' macro.  Hence it is C++11 only.

[[Imported from SVN: r9195]]

It makes it difficult to be sure that an explicitly
requested type is really handed over to every place.

While we are at it: reverse the order of the template
parameters.  Now first comes the type, then the dimension.
This is more like FieldVector and friends, and hence
should be less confusing.

[[Imported from SVN: r8148]]

[[Imported from SVN: r8145]]

[[Imported from SVN: r7414]]

[[Imported from SVN: r7374]]

[[Imported from SVN: r7097]]

[[Imported from SVN: r6543]]

[[Imported from SVN: r6436]]

[[Imported from SVN: r6430]]

[[Imported from SVN: r6426]]

[[Imported from SVN: r5993]]

[[Imported from SVN: r5991]]

[[Imported from SVN: r5931]]

[[Imported from SVN: r5791]]

[[Imported from SVN: r5783]]

[[Imported from SVN: r5698]]

[[Imported from SVN: r5696]]

[[Imported from SVN: r5668]]

[[Imported from SVN: r5547]]

[[Imported from SVN: r5543]]

[[Imported from SVN: r5532]]

[[Imported from SVN: r5526]]

A rudimentary class implementing tuples of real numbers as a Riemannian manifold.  Mainly for testing

[[Imported from SVN: r5514]]