Document display-buffer and other window changes in Lisp manual.

Document display-buffer and other window changes in Lisp manual.

* doc/lispref/windows.texi (Window History): New node.  Move text here
from Buffers and Windows.
(Switching Buffers): Rename from Displaying Buffers, since we
don't document display-buffer here; callers changed.  Document
FORCE-SAME-WINDOW arg to switch-to-buffer and
switch-to-buffer-other-frame.  Delete duplicate
replace-buffer-in-windows doc.
(Choosing Window): Document display actions.