Add manual doc on STL-compatible iterators

doc/snippets/Tutorial_range_for_loop_1d_cxx11.cpp

@@ -0,0 +1,4 @@
+VectorXi v = VectorXi::Random(4);
+cout << "Here is the vector v:\n";
+for(auto x : v) cout << x << " ";
+cout << "\n";

doc/snippets/Tutorial_range_for_loop_2d_cxx11.cpp

@@ -0,0 +1,5 @@
+Matrix2i A = Matrix2i::Random();
+cout << "Here are the coeffs of the 2x2 matrix A:\n";
+for(auto x : A.reshaped())
+  cout << x << " ";
+cout << "\n";

doc/snippets/Tutorial_std_sort.cpp

@@ -0,0 +1,4 @@
+Array4i v = Array4i::Random().abs();
+cout << "Here is the initial vector v:\n" << v.transpose() << "\n";
+std::sort(v.begin(), v.end());
+cout << "Here is the sorted vector v:\n" << v.transpose() << "\n";

doc/snippets/Tutorial_std_sort_rows.cpp

@@ -0,0 +1,5 @@
+ArrayXXi A = ArrayXXi::Random(4,4).abs();
+cout << "Here is the initial matrix A:\n" << A << "\n";
+for(auto row : A.rowwise())
+  std::sort(row.begin(), row.end());
+cout << "Here is the sorted matrix A:\n" << A << "\n";