Adds Stalker as a new class evolution prodigy for Rogue.

While wearing no heavy armor (including helms, boots and gloves) and wielding no weapons:
- The Stalker's actions will never break Stealth.
- Effects normally triggered by exiting Stealth will trigger when landing an unarmed critical strike against an adjacent foe (cooldown 8 ).
- Lethality and Dagger Mastery will apply their effects to gloves.
- The Stalker is considered to be wielding Dual Weapons, using unarmed combat stats for both main hand and offhand (damage penalty applies).

Fixes Stalked so that it does NOT prevent you from entering the world map,
and disappears when you change levels.