Allow generator functions to access the seed

[jslyemath]

Sometimes you just run into an outcome that is very hard to randomize. But, one could still make 20 versions of the outcome for their students to practice with the web viewer. In such use cases, one must have a way of ensuring that we have a 1-to-1 mapping of the 20 versions and seeds 0-19. Allowing a generator function to access the current seed would be (in my mind) the easiest way of doing this.

More interesting capabilities could result from this, such as (off the top of my head): if the end user wants a certain difficulty progression from seeds 0-4 that then loops every 5 seeds.