modpython: Make strings to be stringable.

Now you can use str() on objects of znc.String.
The same is true for arguments which represent CString&.

modules/modpython/modpython.i

@@ -106,6 +106,18 @@ public:
 	CString s;
 };
 
+%extend CPyRetString {
+	CString __str__() {
+		return $self->s;
+	}
+};
+
+%extend String {
+	CString __str__() {
+		return $self->s;
+	}
+};
+
 %extend CModule {
 	MCString_iter BeginNV_() {
 		return MCString_iter($self->BeginNV());