fix: -1 Fel per 2 teeth lost

[baaroth]

Hi,

My character just lost a bunch of teeth and I noticed the script was too harsh on the Fel malus, compared to what the rulebook says.
This is the fix I used in the campaign.

I let the "-1" when there is no tooth count but I'm not sure if this is the right value (if no count means 1 tooth, malus should be 0)

Thanks for letting players (who are proficient in JS) fix scripts on the fly BTW, my DM was glad :)

Fixes #2613