disable not-modified

[Dan Jacobson]

I saw a message blurt by in the minibuffer, so I used C-h l to see
what the heck caused it, and found:

"ESC ~ runs the command not-modified,
Mark current buffer as unmodified, not needing to be saved."

Well goodness gracious, read no further. Put the cursor at the end of
(disable-command 'not-modified)
and hit ^X^E today!

I recommend that it be disabled by default too.
Why in my ~20 years of using this jazz, I never felt bad about all the
safety checks.  Accidentally typing M-~ sounds like a good way to lose
one's work.