forward_line(buffer, body_lines) is not a real scrolling. We need to move the top_line to have a nice effect.

and while there improve the error message.

the new `meta.data' field will be useful for holding completions data.

"no prev item" (or next) can be misleading during a completing-read

* cmd.c (cmd_previous_completion): add previous-completion (cmd_next_completion): add next-completion (cmd_insert_current_candidate): add insert-current-candidate * minibuffer.c (enter_minibuffer): support completions in minibuffer