I just published to the Inbox, the class I've been using as my
Singleton superclass.  3 class-side methods, +1 new one for Squeak.  I
like #current as the nomenclature because:

  - it is aptly descriptive, the "current" singular instance of this
class (which can be replaced, via #current:).
  - The meaning of #default seems more ambiguous.  The default for what?
  - #theInstance or #soleInstance seems to reject the notion of
alternates, as if there is only "the one" eternal instance.

Not a big deal, unifying the Singleton api can simply help with
tidiness.  We could migrate various singletons to inherit the behavior
from this one and get rid of their repetitious accessors, et al.

 - Chris