customize dont offer to save session changes

[Järneström Jonas]

>From a user-friendly program I expect to be notified upon exit, if I
have changed options in the session but not saved them, with a list of
the options and their currrent values, and a query if I want to save
them for the next session. I think Customize should include such a
mechanism. I dont think anyone likes losing settings without being
warned, for example absolute file names or other long handwritten
strings.