* In LU solvers: no need anymore to use row-major matrices

* Matrix: always inherit WithAlignedOperatorNew, regardless of
vectorization or not
* rename ei_alloc_stack to ei_aligned_stack_alloc
* mixingtypes test: disable vectorization as SSE intrinsics don't allow
mixing types and we just get compile errors there.

test/mixingtypes.cpp

@@ -24,6 +24,7 @@
 // Eigen. If not, see <http://www.gnu.org/licenses/>.
 
 #define EIGEN_NO_STATIC_ASSERT // turn static asserts into runtime asserts in order to check them
+#define EIGEN_DONT_VECTORIZE // SSE intrinsics aren't designed to allow mixing types
 #include "main.h"