Remove unused code and migrate to CMake build system.

cpp/classes/ClassA.h

@@ -0,0 +1,23 @@
+#ifndef POINTER_CLASSA_H
+#define POINTER_CLASSA_H
+#include "IComparable.h"
+
+
+class ClassA : public IComparable {
+// private
+
+public:
+    // public
+    void Print();
+    int CompareTo(IComparable* other) override;
+
+protected:
+    // protected
+
+private:
+    // private
+    int _number = 0;
+};
+
+
+#endif //POINTER_CLASSA_H