Lack of asterisk when file got modified outside of QtCreator and the user didn't reload it

Step to reproduce:
1) Save some file from QtCreator - the file isn't marked as modified.
2) Modify the file outside of QtCreator
3) When back to QtCreator answer not to reload changed file.
4) The file inside QtCreator still isn't marked as modified, however it has most probably a different contents in this context. So it should be marked with asterisk.

I think we should mark all changed files outside of QtCreator with asterisk just before we show the message box. When we decide to reload them asterisks should gone. If we decide not to reload them, the asterisks should stay.