Add dired-hide-details-mode. (Bug#6799)

Add dired-hide-details-mode.  (Bug#6799)

* locate.el (locate-mode): Set parent mode property to dired-mode.

* find-dired.el (find-dired): Call dired-insert-set-properties on
initial information line.  Set process mark on end of buffer.
(find-dired-sentinel):
Call dired-insert-set-properties on summary.

* dired.el (dired-hide-details-hide-symlink-targets)
(dired-hide-details-hide-information-lines): New options.
(dired-insert-directory):
Set properties after final treatment of output.
(dired-insert-set-properties):
Set dired-hide-details-* properties.
(dired-mode-map): Bind dired-hide-details-mode.
(dired-mode): Set buffer-invisibility-spec to a list.
(dired-next-line): Skip hidden lines.
(dired-previous-line): Use dired-next-line.
(dired-hide-details-mode): New minor mode.
(dired-hide-details-update-invisibility-spec): New function.