I think that because MatrixFunctions is in unsupported/ and MatrixBase is
not, doxygen does not include the MatrixBase methods defined and documented
in the MatrixFunctions module with the other MatrixBase methods. This is a
kludge, but at least the documentation is not lost.
This does the job but it is only a first version. Further plans:
improved docs, more tests, improve code by refactoring, add convenience
functions for sine, cosine, sinh, cosh, and (eventually) add the matrix
logarithm.
The //@{ ... //@} in unsupported/Eigen/MatrixFunctions for some reason
caused doxygen to list the constructor of the MatrixExponential class
as a separate function in the MatrixFunctions module without any reference
to the class; very confusing.
