Grammar refactoring

* Grammar refactoring WIP

* ISerializer.grammar

* Fixing various bugs in the grammar

* Small touch that improoves performance

* Fix unknown values grammar

* Various fixes

* Serialization refactoring to drop suboject logic

* Details fixed

* Entity attributes initialization refactoring

* JSDoc error fixed

* Rename value key to default

* Remove useless default

* Revert string keys

js/entity/ObjectReferenceEntity.js

@@ -3,8 +3,12 @@ import IEntity from "./IEntity.js"
 export default class ObjectReferenceEntity extends IEntity {
 
     static attributes = {
-        type: "",
-        path: "",
+        type: {
+            default: "",
+        },
+        path: {
+            default: "",
+        },
     }
 
     static {