Fix behavior of with-temp-buffer-window (Bug#16816, Bug#17007).

Fix behavior of with-temp-buffer-window (Bug#16816, Bug#17007).

* window.el (with-temp-buffer-window): Don't make BUFFER-OR-NAME
current (Bug#16816, Bug#17007).
(with-current-buffer-window): New macro doing the same as
`with-temp-buffer-window' but with BUFFER-OR-NAME current.
* help.el (help-print-return-message): Warn in doc-string to not
use this in `with-help-window'.
(describe-bindings-internal): Call `describe-buffer-bindings'
from within help buffer.  See Juanma's scenario in (Bug#16816).
(with-help-window): Update doc-string.
* dired.el (dired-mark-pop-up):
* files.el (save-buffers-kill-emacs):
* register.el (register-preview): Use `with-current-buffer-window'
instead of `with-temp-buffer-window'.
* display.texi (Temporary Displays): Rewrite descriptions of
`with-output-to-temp-buffer' and `with-temp-buffer-window'.
* help.texi (Help Functions): Rewrite description of
`with-help-window'.