[Ready] Mutcat thresholds

[KA101]

Starting with enforcing Purifiability on the IV purifier, and the prereq slots are now working as intended.

Boolean is in. Couple days later, so is the trait-gain and the traits.

It all works, and the infrastructure is fully operational. Thanks to vede on the IRC, it's even streamlined a bit. (Much appreciated.) Follow-up PRs will be along shortly to fill it out and add a special-effects budget.

Equation converted and aggravating brace-glitch fixed. Unfortunately, it's gonna need a manual merge now, apparently, so we may be waiting longer..

[kevingranade]

The code looks sound, it does need some actual traits that use the threshold and 2nd prerequisite list for merge.

[dwarfkoala]

Hrm, let me see if I understand this.

If you mutate enough along a line, you can get non-purifiable traits that indicate you've gone beyond the point of no return, which allows you to gain the more intense mutations along those chains. A threshold will only occur when you've surpassed a certain point in a single mutation line, and once you've thresholded, you cannot gain a second threshold.

Some questions to ask:
Can you gain traits that do not require a threshold when you've gone beyond a threshold?

If you mutate, will your post-threshold traits ever be canceled out by that mutation?

Are post-threshold traits purifiable? Even if you can't go back to humanity, can you at least go back to not-completely-a-bear?

[KA101]

Thresholds require you to have a certain amount of "category strength", and become more likely as your strength in the category increases. (Quickest way to estimate category strength is to check the character's dreams. If they're frequent and specific, you're likely eligible.) One threshold per character, and no, they're not purifiable.

Yes, you continue to gain traits that didn't need a threshold as you normally would, for now at least. I'm thinking one effect of thresholds will be to make category-enforcement much harsher.

Traits that require a Threshold as a prerequisite can be affected like any other trait. Non-purifiability is a separate boolean. You could set Rough Skin to non-purifiable if you wanted. Don't know why you'd do that, but you could.

Likewise, requiring a Threshold doesn't require non-purifiability. Some traits may be permanent. Others, not.

(And there's nothing that prevents one trait from removing a non-purifiable trait. The system's pretty tinkerable.)