Renamed PlainMatrixType to PlainObject (Array != Matrix).

Renamed ReturnByValue::ReturnMatrixType ReturnByValue::ReturnType (again, Array != Matrix).

Eigen/src/Array/Array.h

@@ -41,7 +41,7 @@ class Array
     EIGEN_DENSE_PUBLIC_INTERFACE(Array)
 
     enum { Options = _Options };
-    typedef typename Base::PlainMatrixType PlainMatrixType;
+    typedef typename Base::PlainObject PlainObject;
 
   protected:
     using Base::m_storage;

Eigen/src/Array/ArrayBase.h

@@ -97,7 +97,7 @@ template<typename Derived> class ArrayBase
     /** \internal the plain matrix type corresponding to this expression. Note that is not necessarily
       * exactly the return type of eval(): in the case of plain matrices, the return type of eval() is a const
       * reference to a matrix, not a matrix! It is however guaranteed that the return type of eval() is either
-      * PlainMatrixType or const PlainMatrixType&.
+      * PlainObject or const PlainObject&.
       */
     typedef Array<typename ei_traits<Derived>::Scalar,
                 ei_traits<Derived>::RowsAtCompileTime,
@@ -105,7 +105,7 @@ template<typename Derived> class ArrayBase
                 AutoAlign | (ei_traits<Derived>::Flags&RowMajorBit ? RowMajor : ColMajor),
                 ei_traits<Derived>::MaxRowsAtCompileTime,
                 ei_traits<Derived>::MaxColsAtCompileTime
-          > PlainMatrixType;
+          > PlainObject;
 
 
     /** \internal Represents a matrix with all coefficients equal to one another*/

Eigen/src/Array/VectorwiseOp.h

@@ -462,7 +462,7 @@ template<typename ExpressionType, int Direction> class VectorwiseOp
 
     const Homogeneous<ExpressionType,Direction> homogeneous() const;
 
-    typedef typename ExpressionType::PlainMatrixType CrossReturnType;
+    typedef typename ExpressionType::PlainObject CrossReturnType;
     template<typename OtherDerived>
     const CrossReturnType cross(const MatrixBase<OtherDerived>& other) const;