Return current value of point in WINDOW.
WINDOW must be a live window and defaults to the selected one.
For a nonselected window, this is the value point would have if that
window were selected.
Note that, when WINDOW is selected, the value returned is the same as
that returned by `point' for WINDOW's buffer. It would be more strictly
correct to return the `top-level' value of `point', outside of any
`save-excursion' forms. But that is hard to define.
(fn &optional WINDOW)