Yet another run at reduce (collect)

[Doug Lea]

While scoping out this form of solution, Brian noticed that the
new collecting form of reduce is overload-hostile to
one of the existing reduce methods. (that is, has the same arity
and has mutually-confusable lambda args.) Having been traumatized
by this problem last week, I think we need to do something about this.
He is not yet convinced that we will need to change this. I am.

I propose renaming this form "collect", and the corresponding
interface to Collector. The underlying concept here is,
in Fortress-ese, catamorphic reduction, but the closest
non-weird term is "collect". Much closer than "accumulate".

And further, I think this is a net positive win in terms of
understandability. For example:

    reduce(intoList()) => collect(intoList())

The name provides a pleasant and appropriate clue that it is
something often applicable to Collections.

Try it out on other examples.
I think you will like it better unless you are Brian :-)

And if we don't do this, people will be getting mile-long
overload ambiguity messages from Javac in surprising
contexts.

-Doug