* allow matrix dimensions to be 0 (also at compile time) and provide a specialization

of ei_matrix_array for size 0
* adapt many xprs to have the right storage order, now that it matters
* add static assert on expressions to check that vector xprs
  have the righ storage order
* adapt ei_plain_matrix_type_(column|row)_major
* implement assignment of selfadjointview to matrix
  (was before failing to compile) and add nestedExpression() methods
* expand product_symm test
* in ei_gemv_selector, use the PlainObject type instead of a custom Matrix<...> type
* fix VectorBlock and Block mistakes

Eigen/src/Core/Redux.h

@@ -37,7 +37,7 @@
 template<typename Func, typename Derived>
 struct ei_redux_traits
 {
-private:
+public:
   enum {
     PacketSize = ei_packet_traits<typename Derived::Scalar>::size,
     InnerMaxSize = int(Derived::IsRowMajor)
@@ -55,11 +55,11 @@ private:
 public:
   enum {
     Traversal = int(MayLinearVectorize) ? int(LinearVectorizedTraversal)
-                  : int(MaySliceVectorize)  ? int(SliceVectorizedTraversal)
-                                            : int(DefaultTraversal)
+              : int(MaySliceVectorize)  ? int(SliceVectorizedTraversal)
+                                        : int(DefaultTraversal)
   };
 
-private:
+public:
   enum {
     Cost = Derived::SizeAtCompileTime * Derived::CoeffReadCost
            + (Derived::SizeAtCompileTime-1) * NumTraits<typename Derived::Scalar>::AddCost,