Finally the importing macro is named EIGEN_BASIC_PUBLIC_INTERFACE
because it does not only import the ei_traits, it also makes the base class
a friend, etc.
with minimal code duplication. There now are only two (2)
const_cast remaining in the whole source code.
- eigen2 now fully allows copying a row-vector into a column-vector.
added a unit-test for that.
- split unit tests, improve docs, various improvements.