Reintroduce pop-to-buffer-same-window; use it for previous users of same-window-*.

Reintroduce pop-to-buffer-same-window; use it for previous users of same-window-*.

* window.el (pop-to-buffer-same-window): New (reinstated) fun.

* cmuscheme.el (run-scheme, switch-to-scheme):
* cus-edit.el (customize-group, custom-buffer-create)
(customize-browse):
* info.el (info):
* shell.el (shell):
* mail/sendmail.el (mail):
* progmodes/inf-lisp.el (inferior-lisp): Use it.

Fixes: debbugs:9532