Make help and view-mode work with new buffer display facilities.

Make help and view-mode work with new buffer display facilities.

* help.el (help-window): Remove variable.
(help-window-point-marker, temp-buffer-max-height)
(temp-buffer-resize-mode, help-window-select): Rewrite doc-strings.
(help-print-return-message): Don't set help-window.
(resize-temp-buffer-window): Rewrite cod eand doc-string.
(help-window-setup-finish): Remove.
(help-window-display-message, help-window-setup)
(with-help-window): Major rewrite based on new
display-buffer-window variable.

* help-mode.el (help-mode-finish): Remove help-window related
code.

* view.el (view-exits-all-viewing-windows): Remove reference to
view-return-to-alist in doc-string.
(view-return-to-alist): Make obsolete.
(view-buffer): Call pop-to-buffer-same-window and remove
undo-window code.
(view-buffer-other-window): Call pop-to-buffer-other-window and
simplify code.  Ignore second argument.
(view-buffer-other-frame): Call pop-to-buffer-other-frame and
simplify code.  Ignore second argument.
(view-return-to-alist-update): Make obsolete.
(view-mode-enter): Rename second argument to QUIT-RESTORE.
Rewrite using quit-restore window parameters.
(view-mode-exit): Rename second argument to EXIT-ONLY.  Rewrite
using quit-restore-window.
(View-exit, View-exit-and-edit, View-leave, View-quit)
(View-quit-all, View-kill-and-leave): Call view-mode-exit with
appropriate arguments.
(view-end-message): Use quit-restore window parameter.