[Fix] Subclass Links (#1069)

* Attempt at making subclass aware of its class

* Update compendium classes/subclasses

* Fixed multiclass

* Update compenidum browser subclass class filter

* Added migration for subclass.linkedClass

* Using foundry's isNewer function rather than custom one

* Added migration for existing actor features

---------

Co-authored-by: Dapoolp <elcatnet@gmail.com>

module/data/item/feature.mjs

@@ -29,6 +29,7 @@ export default class DHFeature extends BaseDataItem {
                 nullable: true,
                 initial: null
             }),
+            multiclassOrigin: new fields.BooleanField({ initial: false }),
             identifier: new fields.StringField()
         };
     }