More abilities, implemented support for form inheritance

PkmnLib.Dynamic/Models/Pokemon.cs

@@ -784,6 +784,7 @@ public class PokemonImpl : ScriptSource, IPokemon
     {
         var previous = HeldItem;
         HeldItem = item;
+        this.RunScriptHook(x => x.OnAfterHeldItemChange(this, previous, item));
         return previous;
     }
 
@@ -799,6 +800,7 @@ public class PokemonImpl : ScriptSource, IPokemon
         }
         var previous = HeldItem;
         HeldItem = null;
+        this.RunScriptHook(x => x.OnAfterHeldItemChange(this, previous, null));
         return previous;
     }