Add a method to force a recheck of available choices in a Story

Once you get into a choice point, currentChoices are locked even if you set a relevant global variable externally.

e.g.:

*{myVariable} choice1
*choice2

would only return choice2 if you checked it, even if myVariable is global and you set it before checking, but after having the story continue up to the choice point.

In the game I'm currently making, we "solved" this by always saving the last storypath a Story was at before a choice and, in the cases where it matters, going back to it and continuing untill we're back to it. This solves the problem, but it breaks Tunnels, which kinda sucks.

I've also tried solving it with LoadStoryState, but it didn't seem to work as well (tbh I don't really remember why, maybe it just does the same exact thing and we didn't realize at the time the problem were the tunnels).

Anyway, that's all to say, something like a RefreshCurrentChoices that could rerun the check for available choices would be great.

I considered going into the Ink sourcecode and doing it myself, haven't done it just because we're on a short time limit for this project and I didn't want to risk it.