Update simplex.js

requires json-tree from luxid with changed super.settings.edit :
"edit": {
        "id": {
          "editmode": "none"
        },
        "context": {
          "editmode": "select",
          "lookupurl": "/json/xobjects/lookup/context"
        },
        "usertype": {
          "editmode": "select",
          "lookupurl": "/json/xobjects/lookup/usertype"
        },
        "created_at": {
          "editmode": "none"
        }
      }