get rid of using namespace Eigen in sample code

doc/examples/Tutorial_ArrayClass_accessors.cpp

@@ -1,24 +1,21 @@
 #include <Eigen/Dense>
 #include <iostream>
 
-using namespace Eigen;
-using namespace std;
-
 int main()
 {
-  ArrayXXf  m(2,2);
+  Eigen::ArrayXXf  m(2,2);
   
   // assign some values coefficient by coefficient
   m(0,0) = 1.0; m(0,1) = 2.0;
   m(1,0) = 3.0; m(1,1) = m(0,1) + m(1,0);
   
   // print values to standard output
-  cout << m << endl << endl;
+  std::cout << m << std::endl << std::endl;
  
   // using the comma-initializer is also allowed
   m << 1.0,2.0,
        3.0,4.0;
      
   // print values to standard output
-  cout << m << endl;
+  std::cout << m << std::endl;
 }