Wounds and the first aid skill have undergone some changes.
Most important of these is the fact that wounds are no longer just "bound up"
or not: depending on one's skill in first aid, medication can result in a
loosely bound, bound or securely bound wound. A better bound wound will heal
faster and have a lower chance of worsening.
Wound conditions will worsen with the passage of time: a securely bound wound
will become "bound", then "loosely bound", and then the bandage will fall off.
At any point during this process, of course, you can remove the old bandage
and replace it with a fresh one.
Neglecting an open wound can be dangerous, as it might become dirty and then
infected. Infected wounds will take longer to heal and have a higher chance
of worsening. Unless you're a Troll, that is.
The chances of (at least partial) success of the first aid skill have
increased. However, binding a severe wound without sufficient skill will still
take some time.
The severity of wounds (light, deep, serious, grievous, critical) and the
effect of wounds on characters remain unchanged.
Many thanks to Scar for the idea and his valuable help.