int on_consume( int max )

Called whenever the object is consumed with an eat or a drink command.
The 'max' is the maximum amount of food/drink value to be consumed.
If the object should be destroyed after being consumed, it MUST be done
in this event! (This is to allow for partial consumption, for things
like large pieces of food or drinks). You may ignore max if you choose,
and just add the full food value, but I recommend you allow for partial
consumption on larger pieces of food.

on_consume is expected to do its own messaging. That is, if a message should
be displayed when you eat or drink the item (usually always true), then you
should display a message.

If the food item wasn't consumable at all, and you want the verb to handle
the error message, return 0. If anything was eaten, or if you gave your own
error message, then return 1.
