cleanup: remove copy contructors when the compiler is able to generate a satisfactory

default copy constructor; remove useless static_cast's; some misc cleanup.

Eigen/src/Core/Product.h

@@ -75,9 +75,6 @@ template<typename Lhs, typename Rhs> class Product : NoOperatorEquals,
       assert(lhs.cols() == rhs.rows());
     }
     
-    Product(const Product& other)
-      : m_lhs(other.m_lhs), m_rhs(other.m_rhs) {}
-    
   private:
     static const int _RowsAtCompileTime = Lhs::RowsAtCompileTime,
                      _ColsAtCompileTime = Rhs::ColsAtCompileTime;