Fix Forewarn message
Ugly hack to fix burn+Explosion damage
Currently, if a burned Pokemon explodes in doubles, all targets except
the first will take full damage, because it's fainted (and no longer
burned) by the time those damage calculations are done.

The correct solution is to do all damage calculations before dealing
any damage, which I will do someday. Today is not that day.

Today, we move fainting the Explosion user to after damage is dealt.
Which, aside from making the faint order wrong, doesn't really have
any other consequences, and is better than the current buggy
damage calculation.