Fix formblob-ing NPCs

[sethsimon]

This fixes an issue reported by KliPeH in the forums:

I noticed a neutral NPC approaching my shelter so I told him to drop his weapon and bugger off. He complied, dropping his weapon and fleeing in the opposite direction, straight towards an amoebic mold. When he got close to it he started attacking, which triggered the mold to debuff him with its usual "slimed" effect - except the debuff affected me and not him. I got a log message saying I am "covered in thick goo!", even though I was at least 30 tiles away from their little brawl. When I checked my (@)ttribute tab, the effect was there indeed. I was certain the debuff shouldn't affect everybody in sight, only those who are in close proximity to the enemy. Just like boomer bile only affecting you if you're in the explosion radius.