Merge branch 'worldy-knowledge' into 'master'

Change Worldly Knowledge to use class.EscortRewards interface

This change will add the missing cunning/scoundrel to worldly knowledge, and make it automatically support any escort trees from addons.

It is also tweaked to give antimagic escort trees to non-antimagic player if they don't have magic skills, just equivalent to the escort.

Still, it have no support for tinkers, since tinker will eat your category point in another chat. Maybe tinker should need to provide a newer interface for it if we want to intergrate it.

See merge request !686