Add C++ nested class example

This also reverts the nested class additions to the Java/C# 'class' example
so that the 'class' example remains identical across different language modules

Examples/csharp/nested/example.h

@@ -0,0 +1,48 @@
+#include <string>
+
+/** Design a motor car from various components */
+struct MotorCar {
+
+  /** Information about an opinion of the design of a car component */
+  struct DesignOpinion {
+    bool itrocks;
+    std::string reason;
+    static int AceDesignCount;
+    static int TotalDesignCount;
+    static int PercentScore();
+  };
+
+  /** Wheels component */
+  struct Wheels {
+    enum Shape { Round, Square };
+    Wheels(Shape shape, size_t count);
+    DesignOpinion Opinion();
+  private:
+    Shape shape;
+    size_t count;
+  };
+
+  /** Windscreen component */
+  struct WindScreen {
+    WindScreen(bool opaque);
+    DesignOpinion Opinion();
+  private:
+    bool opaque;
+  };
+
+  /** Factory method for creating a car */
+  static MotorCar DesignFromComponents(const std::string &name, const Wheels &wheels, const WindScreen &windscreen);
+
+  std::string Name() {
+    return name;
+  }
+
+  /** Get an overall opinion on the car design */
+  std::string WillItWork();
+
+private:
+  MotorCar(const std::string &name, const Wheels &wheels, const WindScreen &windscreen);
+  std::string name;
+  Wheels wheels;
+  WindScreen windscreen;
+};