1 * PointerList<T>:List<T> -> PointerList<T>:List<T*>
3 * PCursor -> Pointer_cursor / PointerCursor ?
5 * efficient copy cons for List
13 * use template handle in handle.hh for strings.
15 * Restricted cursor/list: make sublist from a list, and use rcursor as if list is as big as the sublist.