Expose mut ability

rpg_components/src/items/ability_book.rs

@@ -196,6 +196,10 @@ impl<A: Ability> AbilityBook<A> {
         &self.ability
     }
 
+    pub fn ability_mut(&mut self) -> &mut A {
+        &mut self.ability
+    }
+
     pub fn addons(&self) -> &AbilityAddonCollection {
         &self.addons
     }