Adds logging when gas-exuding seeds are planted

Created by: Kammerjunk

Instead of having to check all strange and modified plants for fingerprints and their seeds for exude_gasses, this'll add a log whenever a seed which exudes gasses is planted. Should it add an investigation log to the person planting it? I'm not sure. I can do that if it should be added, but I'd have to find out how exactly first. Should be easy, I guess.