bug#419: switch-to-buffer too easy to create new buffers

[jidanni]

Regarding
  C-x b runs the command switch-to-buffer
  If BUFFER does not identify an existing buffer,
  then this function creates a buffer with that name.

Which 99% of the time is not what the non-pro user wants. He hardly
ever wants to create new unnamed buffers, but instead switch to an
existing buffer, unless he is a pro. So there perhaps should be a
variable, default nil, that won't let him press RETURN unless he types
an existing buffer name.

True, pros will TAB around in the dark to make sure they have a match,
but still...

So now require C-u C-x b to allow creation of new buffers... ah yes.
Oops, stepped on "&optional NORECORD".

P.S., implementing my above training wheels proposal will surely mess
up scripts, so perhaps only have it kick in if we detect we are typing
into the minibuffer.

Or mark "wontfix" quick now, see ya, bye.

Or add a new function, switch-to-existing-buffer that can be bound to
C-x b, with the C-u jazz to create new buffers...