bug#51883: 29.0.50; Command to get accidentally deleted frames back

[Gregory Heytings]

> I meant "C-x 5 u" to undelete the most recently deleted frame, and 1 to 
> 16 to mean undelete the penultimate frame etc.  Basically ARG of N means 
> undelete the N+1st previously deleted frame.  I just didn't want the ARG 
> of zero to be handled specially.

Okay, I'll do that.

So, just to make this crystal clear:

C-x 5 u -> undelete most recently deleted frame
C-u 0 C-x 5 u -> undelete most recently deleted frame
C-u 1 C-x 5 u -> undelete second most recently deleted frame
...

and

C-u C-x 5 u -> error

?