Fix disableFreeze flag

[VasilisTert]

The flag disableFreeze is in collection not in this. Now it returns undefined so the object is always cloned.

[AntonNevsgodov]

Until this PR is merged (never, I guess), this monkeypatch can be a viable solution:

// TypeScript
import LokiJS from 'lokijs';

// Make Resultset.disableFreeze a property with getter that returns Collection.disableFreeze property value.
Object.defineProperty((LokiJS as any).Resultset.prototype, 'disableFreeze', {
  get() {
    return this.collection.disableFreeze;
  },
});