Sorted Map/AA for D2.0

[Brian White]

> Currently, both v1 and v2 implement associative arrays, but neither the
> keys or values are sorted. This is not a big problem unless you need to
> continually access the data in sorted order.

Right.  I want the keys sorted.  I have a task where I'll be inserting 
into the map sporadically but will be accessing it freely and I need it 
sorted.  A "heap" would suffice, too, as I really is O(1) access to the 
smallest element.

-- Brian