Commit Briefs
move help to its own file
in order to do so, we also have to export some internal variables from ui (the width and height of the window). Not the best possible outcome, but are used only in recompute_help, and can be dropped later. Also, move wrap_page to wrap.c.
refactor struct vline
the new `meta.data' field will be useful for holding completions data.
support completions in minibuffer + related interactive fns
* 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