Display all 132 possibilities? (y, n, or t) t=time!

[積丹尼 Dan Jacobson]

Super duper idea: you know when we hit TAB and it says
Display all 132 possibilities? (y or n)

Well, that happens to be the 'ls -a' format it is asking about.

Well, who says that is the most natural format or the format we want at
that time?

What if occasionally we want the 'ls -t' or 'ls -ta' format?

Well, it would be nice to have it ask instead
Display all 132 possibilities? (y, n, or t)

But wait, what if there are not so many completions to trigger the question?
(Well, in that case one could say that alphabetical order is OK as it
isn't that difficult to find what one is looking for among so few items.)

Anyway, one might remove "in alphabetical order" from

       print-completions-horizontally (Off)
              If  set  to  On,  readline will display completions with matches
              sorted horizontally in alphabetical order, rather than down  the
              screen.

as in the future that might not always be the case!

Anyway, in addition to t for time, there could be r for reverse. (But no
rt or tr as it should act on the first character it reads.)