Intentionally spoil foodpois mechanics when it happens

Intentionally spoil foodpois mechanics when it happens

One of the huge strengths of NetHack is that there's a lot of
mechanical content in it; you can continue learning about the game
more or less continuously, and when you die, it's usually possible
to figure out what you did wrong and avoid that for future games.
There are two parts to this: a) a death should only happen if the
player didn't play perfectly, b) the nature of the problem should
be clear.

FoodPois status meets a) just fine, but not b); food poisoning
mechanics tend (based on my research) to actively give the wrong
impression to new players. (Normally, something along the lines of
"corpses are sometimes randomly dangerous", which is insidious in
the sense that it'll cause players to leave them as a last resort
and thus never discover what they're doing wrong.) The easiest way
to fix this is to explain what the rule is explicitly.
Additionally, this should hopefully go some way towards changing
the incorrect perception many people who haven't played (any/much)
NetHack have that the game is arbitrarily cruel... It's important
to get the "everything happens for a reason" attitude across from
an early stage, by tying it to an event like this that's commonly
seen by new plyers.

Experienced players should not be affected much if at all by this
change, because they hardly ever get food poisoning anyway.

(Note: there are actually two main mechanics related to food
poisoning, one widely applicable, one much more subtle. The message
here is focused mainly on the common case, but doesn't actually
contradict the rare case, and attentive players may be able to
deduce both mechanics from the one message. Most likely, players
will hit the common case, see the message, learn the common case,
and some time later hit the rare case, get the message again, and
read it more carefully this time.)