Proposal: Tidy up and export PSQ from base

[Edward Z. Yang]

Excerpts from Ian Lynagh's message of Sun May 01 20:26:10 -0400 2011:
> On Sun, May 01, 2011 at 07:58:37PM -0400, Edward Z. Yang wrote:
> > 
> > Though, it seems I'm already too late to the party: GHC.Event.PSQ is
> > stolen from the PSQueue Hackage package, with some modifications (I
> > didn't realize this when I originally made my proposal).  So I hereby
> > amend my proposal:
> > 
> >     I propose we move PSQueue into containers, hereby putting it
> >     on even ground with IntMap.  Its notability for inclusion is hereby
> >     established by its use in the IO Event Manager and its projected
> >     use in Hoopl.
> 
> Why merge the two libraries, rather than just adding PSQueue to the set
> of bootlibs?

I suppose the other works as well.

Cheers,
Edward