This is an optimization for complex matrices, allowing to do only a real multiplication
when a complex multiplication is not needed, e.g. in normalized().
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.
- make vectors use a separate loop unroller, so that copying a
row-vector into a col-vector is now possible
- add much more documentation
- misc improvements
