[engine.i] gnc_budget_get_account_period_note to be freed by the caller

amendment to last commit.

this pair of changes was necessary to allow the GValue to be unset.

bindings/engine.i

@@ -131,6 +131,8 @@ functions. */
 %newobject gnc_localtime;
 %newobject gnc_gmtime;
 
+%newobject gnc_budget_get_account_period_note;
+
 /* Parse the header file to generate wrappers */
 %inline {
   static QofIdType QOF_ID_BOOK_SCM (void) { return QOF_ID_BOOK; }