* 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
* export DBC to text edit
* added saveAs & Copy To Clipboard
* cleanup
* cleanup include
* add test case
* rename variable
* fix precision
old-commit-hash: 80b088c332808439ea9cfe23557fae5a86fb075c