Add a cancel button to an import or export when stuck

[Billbh]

Sometimes the internet connection goes down and exports freeze until we force quit iScore

Please add a cancel button if progress freezes a such as when the server cannot be reached

[FTMSupport]

There is a timeout built in that should abort if no data is received for a certain period of time. If the import/export progress is visible, it means that progress is being made (although it could be going very slow depending on your internet connection). We will add this request to our enhancement list however.