* undo/redo
* display command list to rolling the state backwards or forward
* update detailview after rolling states
* add * to title bar to indicate dbc has changed
* fix signal pointer address changed after removed
* cleanup
* fix id error
* clear undo stack after dbc file changed
* cleanup
* use map
* cleanup
* typo
old-commit-hash: 7c922eafe9d9c8e07de80f8bafcd9b2dc2932c13
Dean Lee