Add doxygen test for nested classes

Examples/test-suite/doxygen_nested_class.i

@@ -0,0 +1,23 @@
+%module doxygen_nested_class
+
+%warnfilter(SWIGWARN_PARSE_NAMED_NESTED_CLASS) DoxOuter::DoxInner;
+
+%inline %{
+
+struct DoxOuter {
+  /** DoxOuter constructor */
+  DoxOuter() {}
+  struct DoxInner {
+    /** DoxInner constructor */
+    DoxInner() {}
+    /** doxInt variable */
+    int doxInt;
+    /** doxShort const variable */
+    static const short doxShort = 1.0;
+    /** doxMethod description */
+    void doxMethod() {}
+    /** doxStaticMethod description */
+    static void doxStaticMethod() {}
+  };
+};
+%}