Seq should auto-close underlying Stream

[lukaseder]

This can be implemented by wrapping the stream via the following pattern:

    class AutoClosingStream<R> implements Stream<R> {

        AutoClosingStream(Stream<R> delegate, Consumer<Optional<Throwable>> onClose) {}

        // Pipeline op
        @Override
        public Stream<R> limit(long maxSize) {
            return new AutoClosingStream(delegate.limit(maxSize));
        }

        // Terminal op
        @Override
        public void forEach(Consumer<? super R> action) {
            terminalOp(() -> delegate.forEach(action));
        }

        private void terminalOp(Runnable runnable) {
            terminalOp(() -> { runnable.run(); return null; });
        }

        private <R1> R1 terminalOp(Supplier<R1> supplier) {
            R1 result = null;

            try {
                result = supplier.get();
                onClose.accept(Optional.empty());
            }
            catch (Throwable e) {
                onClose.accept(Optional.of(e));
                Utils.sneakyThrow(e);
            }

            return result;
        }
    }

Such an AutoClosingStream would need to take care of implementing all future methods, e.g. from JDK 9, etc.

See also jOOQ/jOOQ#4932