the snippet for 'eval' was taking m=m.transpose() as an example of code
that needs an explicit call to eval(), but that doesn't work anymore now
that we have the clever assert detecting aliasing issues.
Renamed "MatrixBase::extract() const" to "MatrixBase::part() const"
* Renamed static functions identity, zero, ones, random with an upper case
first letter: Identity, Zero, Ones and Random.
