C-U prompting

[Daniel L. Weinreb <dlw at SCRC-TENEX>]

I agree that I'd rather not have them cover up the mode line; I think
that I don't like the mode line to go away so much.  The C-U stuff seems
to go away as soon as you give the command to which it applies, so it
doesn't cause trash to accumulate on the screen.  Indeed, it is very
important NOT to display C-U when you are NOT in the state of just
having typed the control-U.

I don't know about the who-state.  That's a good problem.