Tweaks to display-buffer default actions; remove same-window-* autoload forms.

Tweaks to display-buffer default actions; remove same-window-* autoload forms.

* lisp/window.el (display-buffer-alist): Add entry for buffers
previously handled same-window-*.
(display-buffer-alist, display-buffer-default-action)
(display-buffer-overriding-action): Mark as risky.
(display-buffer-alist): Document action function changes.
(display-buffer--same-window-action)
(display-buffer--other-frame-action): New variables.
(switch-to-buffer, display-buffer-other-frame): Use them.
(display-buffer): Rename reuse-frame entry to reusable-frames.
(display-buffer-reuse-selected-window): Function deleted.
(display-buffer-reuse-window): Handle reusable-frames alist entry.
If it's omitted, check pop-up-frames/display-buffer-reuse-frames.
(display-buffer-special): New function.
(display-buffer--maybe-pop-up-frame-or-window): Rename from
display-buffer-reuse-or-pop-window.  Split off special-display
part into display-buffer-special.
(display-buffer-use-some-window): Don't perform any special
pop-up-frames handling.
(pop-to-buffer): Use window-normalize-buffer-to-switch-to.

* lisp/cmuscheme.el:
* lisp/ielm.el:
* lisp/shell.el:
* lisp/mail/sendmail.el:
* lisp/progmodes/inf-lisp.el: Don't set same-window-buffer-names.

* lisp/cus-edit.el:
* lisp/info.el:
* lisp/net/rlogin.el:
* lisp/net/telnet.el:
* lisp/progmodes/gud.el: Don't set same-window-regexps.