Rename model package to actor
Add conditional clause to follow method in Actor

This will be used to check if the two players are in the same region,
because the follow action only shows up on players who are in the same
region (because they must be within visible range).
Moved active prayer effects from Player to Actor
Move PrayerEffect from player package to actor package
Remove unneeded import
Add version tag to Npc class
Rename org.zephyrion.ares.combat to org.zephyrion.ares.actor.combat
Update existing combat files that were missed in previous commit
Make Event class generic
Add more specific exception messages
Move combat package to npc parent

The reason is that the combat behaviors apply only to the Npcs.