ExtJS Models Need Some Work

1. They really need getters. Convert is not a getter. It is a setter that returns a value. Convert is also called before the data is loaded, and before associations are created, meaning you have to do lots of checks for those. Sencha, please add getters, that can still auto-load on forms and grids
2. They really need validation scenarios. These are easy to do. Sencha, just copy Yii's validation scenarios.
3. Please add some events to Models, such as datachanged. I don't want to have to add a model to store just to get notified when it changes.