Rules are not template anymore (it was dumb)

Entities are now managed with unique_ptr to allow polymorphism (and good memory management)
Rules can be added via the Level object
Fixed Rule::findTarget not caring about targetType

TODO : Find why pathfinding (unlikely) or findTarget (most likely) is broken

src/Entity.cpp

@@ -79,6 +79,11 @@ State Entity::getState() const
     return currentState;
 }
 
+EntityType Entity::getType() const
+{
+    return type;
+}
+
 pro_maat::GridPos Entity::getTarget() const
 {
     return target;