Creates a Spliterator over the elements described by this Iterable.

Returns:  a Spliterator over the elements described by this Iterable.

Since:  1.8

@implSpec The default implementation creates an early-binding spliterator from the iterable's Iterator. The spliterator inherits the fail-fast properties of the iterable's iterator.
@implNote The default implementation should usually be overridden. The spliterator returned by the default implementation has poor splitting capabilities, is unsized, and does not report any spliterator characteristics. Implementing classes can nearly always provide a better implementation.