(ibuffer-mode-map): Bind <up> to `ibuffer-backward-line'. Bind
new functions from ibuf-ext.el. Add menu entries for them.
Remove superfluous tooltips.
(ibuffer-toggle-marks): If on a group name, then toggle marks just
in that group.
(ibuffer-mark-interactive): Handle filter groups.
(ibuffer-mark-forward, ibuffer-unmark-forward)
(ibuffer-mark-for-delete, ibuffer-unmark-backward)
(ibuffer-mark-for-delete-backwards): Update docs.
(ibuffer-current-filter-groups): Moved to ibuf-ext.el, and renamed
to `ibuffer-current-filter-groups-with-position'.
(ibuffer-redisplay-engine): Handle
`ibuffer-show-empty-filter-groups'.
(ibuffer-mode): Add some documentation about filter groups.
(ibuffer-mode-map): Bind and add menu entries for most new
functions; also, bind the arrow keys to the movement functions.
(ibuffer-mode-filter-group-map): New.
(ibuffer-mouse-toggle-mark): Handle group names.
(ibuffer-mouse-visit-buffer): Error if the current buffer is
killed.
(ibuffer-skip-properties): New function.
(ibuffer-backward-line, ibuffer-forward-line): Optionally skip
group names. Also, handle new properties.
(ibuffer-visit-buffer, ibuffer-visit-buffer-other-window): Move
error handling to `ibuffer-current-buffer'.
(ibuffer-visit-buffer-other-frame, ibuffer-bury-buffer): Ditto.
(ibuffer-visit-tags-table, ibuffer-do-view-1): Ditto.
(ibuffer-toggle-marks): Add optional group argument.
(ibuffer-mark-interactive): Skip group names.
(ibuffer-current-buffer): Clean up error handling.
(ibuffer-fontify-region-function): Fontify group names.
(ibuffer-map-lines): Add extra group argument. Handle it.
(ibuffer-current-filter-groups): New function.
(ibuffer-redisplay): Handle hidden filtering groups.
(ibuffer-sort-bufferlist): New function, taken from
`ibuffer-insert-buffers-and-marks'.
(ibuffer-insert-filter-group): New function.
(ibuffer-redisplay-engine): Renamed from
`ibuffer-insert-buffers-and-marks'. Handle new filtering groups.
(ibuffer): Add filter-groups argument. Handle it. Use
`save-selected-window'.
(ibuffer-mode): Make `ibuffer-filtering-groups' and
`ibuffer-hidden-filtering-groups' buffer-local.
only moving one line forward.
(ibuffer-map-lines): Preserve point position even if we delete
lines. Only call mapping functions with buffer and mark
arguments; the other two were unused.
(ibuffer-redisplay, ibuffer-update): Always skip special areas.
(ibuffer-current-buffers-with-marks): Don't call `buffer-list'
ourselves; take it as an argument. Caller updated.
(ibuffer-mode): Make mode-class special.
