- rework the coefficients API

- 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

doc/tutorial.cpp

@@ -1,6 +1,6 @@
 #include <Eigen/Core.h>
 
-USING_EIGEN_DATA_TYPES
+USING_PART_OF_NAMESPACE_EIGEN
 
 using namespace std;