Shown unknown game variant message in GUI
Currently when an unknown game variant is detected, it adds a message in the log file and stdout so that the user can easily copy it to the clipboard and report the unknown variant. However this makes the message difficult to notice on some platforms. I think it should also be shown in the GUI in a dialog. And to make it easy to report the unknown game variant, this dialog could have, depending on the features available for the current platform:
- A button to copy the message to the clipboard.
- A button to open the bug tracker and pre-fill the description.
We already have an API to open a URL in OSystem, but the copy to clipboard is currently missing (we have only a paste from clipboard) and would need to be added.