Persist entities in localStorage/sessionStorage, namespaced by their schema id.
class MMO.core.Storage
Namespace
MMO.core
See
MMO.core.Storage#clear only wipes the entries of this collection.
Every key is prefixed with the schema id so two collections never collide, and
const store = new MMO.core.Storage('local', 'SCHEMA://app.entities.User');
store.setItem('current', user);
const user = store.getItem('current');//an MMO.elements.Entity, or null