Make Averguard quests more flexible

These changes remove the previous requirement of having to return to
Guill after finding the Key and the Talisman. Instead, players can
collect both items and head straight for Maddox. Then they only have to
make one trip back to Guill to get their rewards. Of course, they can
still return to Guill to turn those quests at any time in between.

Another change is the ability to grab both the Ukkonen and the Averguard
Tome quests at the same time.