Modified Array Class tutorial, added examples

doc/examples/Tutorial_ArrayClass_addition_scalar.cpp

@@ -0,0 +1,17 @@
+#include <Eigen/Dense>
+#include <iostream>
+
+using namespace Eigen;
+using namespace std;
+
+int main()
+{
+  ArrayXXf a(3,3);
+  
+  a << 1,2,3,
+       4,5,6,
+       7,8,9;
+
+  cout << "a + 2 = " << endl
+       << a + 2 << endl;
+}