TECHNICAL NOTES ABOUT HUNGER
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In order to detect if the player ate an item (to restore the hunger timer),
this mod overrides the on_use callback of all known food items, resetting the
timer and calling the callback to perform the actual healing. This has the
advantage that the hunger timer is reset whenever the player "eats" the item,
but new food items must be explicitly listed on the  script for the mod to
"know" it's food.

At first, this was implemented by checking whether the player's HP increased
since the last check, but this has several disadvantages:

  - It's not possible to have separate "hunger" and "thirst" if the drink
    item increases HP, because this would also be taken as eating.
  - When the HP is at max, eating a food item does not reset the hunger timer
    since there was no increase in HP.
  - Other healing mechanisms (such as the medikit blocks) may interfere with
    the detection.