＊调整提醒事项界面中的table cell
＊加入“事项细节”界面，和与之匹配的类代码
＊加入DataModel
＊add some code for enable edit and delete table cells
* for testing Core Data code
* Core Data codes, with bug on TableView CommintChangesXXX
* fix a bug on TableView :: commitChangesXXX