[RFA] Add "del" as alias to "delete"

[Michael Snyder]

Joel Brobecker wrote:
>>>2006-04-06  Joel Brobecker  <brobecker@adacore.com>
>>>
>>>        * breakpoint.c (_initialize_breakpoint): Add "del" as an alias
>>>        of the "delete" command.
>>>
>>Does anyone think we should make "dele" and "delet" work again too?

Guys, this seems awkward and ad hoc (I realize it's my fault...)

What if we make "delete" a command prefix (like "maint"),
and then just branch from what follows it (eg. breakpoint,
tracepoint, fork, checkpoint, display), with the default to be
breakpoint.

I'm not quite sure why this is broken only now...
it used to work when "delete tracepoint" and
"delete display" were possibilities.