Generators

[Brian Goetz]

I'm looking over our generators.  Currently we have:

   repeat(T)
   repeat(n, T)
   repeatedly(Supplier<T>)
   repeatedly(n, Supplier<T>)
   iterate(T, UnaryOperator<T>)
   cycle(Iterable)

I'd like to pare this down a lot.  Paul and I have been discussing 
techniques for making limit() more efficient, at which point the first 
four can collapse to

   generate(Supplier<T>)

since you can simulate repeat(T) with generate(() -> T) and the limited 
versions with generate().limit().

That leaves us with

   iterate(T, UnaryOperator<T>)
   cycle(Iterable)

and I'm thinking cycle doesn't pull its weight either.  If we took that 
out, we'd be down to the pleasantly small set of:

   generate(Supplier<T>)
   iterate(T, UnaryOperator<T>)

For integer generators, we have

   range(from, to)

and I think we should add

   ints() -> sugar for range(0, MAX_INT)

(Or should ints() be truly infinite, wrapping around?)