bug#33871: 27.0.50; Revert Dired window saved in window configuration

[martin rudalics]

> It should end up where it was initially, i.e. on file names in Dired.
> But this can achieved only by implementing context-aware markers,
> such as used by the package saveplace.el, e.g.:
>
>    ((window-configuration-1
>       ((dired-window-1 . `(lambda () (dired-goto-file 
,(dired-get-filename))))))
>     (window-configuration-2 ...)
>     ...)

Reverting a directory in a window could remember the name of the file
shown at the corresponding line and the offset of 'window-point' on that
line and also the entire contents of the old directory until revert
completes.  As soon as the new contents of the directory have been
established, dired would search the remembered name and position point
at the remembered offset accordingly.  If it does not find that name, it
would have to compare the contents of the old and current contents of
the directory and use some heuristics to position point appropriately.

martin