ag_db_save_identical can now compare based only on chart-related data

This way the chart won’t get recalculated on a name change.

src/ag-db.h

@@ -68,7 +68,9 @@ GList *ag_db_get_chart_list(AgDb *db, GError **err);
 
 AgDbSave *ag_db_get_chart_data_by_id(AgDb *db, guint row_id, GError **err);
 
-gboolean ag_db_save_identical(const AgDbSave *a, const AgDbSave *b);
+gboolean ag_db_save_identical(const AgDbSave *a,
+                              const AgDbSave *b,
+                              gboolean chart_only);
 
 #define AG_DB_ERROR (ag_db_error_quark())
 GQuark ag_db_error_quark(void);