fixed out-of-scope nested class definitions, added a test

enabled nested C structs assignment (still disabled for Octave), added Java runtime test
fixed nested_private test case for Java & C#

Examples/test-suite/nested_scope.i

@@ -0,0 +1,14 @@
+%module nested_scope
+
+%inline %{
+namespace ns {
+	struct Global {
+		struct Outer {
+			struct Nested;
+		};
+		struct Outer::Nested {
+			int data;
+		} instance;
+	};
+}
+%}