(ibuffer-backward-line, ibuffer-forward-line)

(ibuffer-backward-line, ibuffer-forward-line)
(ibuffer-mark-interactive): Use `or' instead of `unless'.
(define-ibuffer-column name): Add summarizer.
(define-ibuffer-column size): Likewise.
(define-ibuffer-column filename): Likewise.
(define-ibuffer-column process): Likewise.  Change BODY's output too.
(define-ibuffer-column filename-and-process): Likewise, likewise.
(ibuffer): Remove local vars `already-in' and `need-update'.