(outline-mode-menu-bar-map): Add entries.

(outline-mode-menu-bar-map): Add entries.
(outline-mode-prefix-map): Match new bindings to those of allout.
(outline-map-region): New fun.
(outline-map-tree): Remove.
(outline-promote, outline-demote): Apply to region if active.
Change the default to apply to the subtree.
(outline-move-subtree-up, outline-move-subtree-down): New funs.
(outline-invisible-p): Add optional `pos' argument.
(outline-next-visible-heading, outline-toggle-children): Use it.
(outline-get-next-sibling): Don't call outline-level at eob.