CHANGED: add Solar data display within the info bar

[dl1bz]

I have changed the procedure for fetching the solar data from the Internet. This fetching is running now in an own thread to avoid blocking the main GTK/GUI thread. Sometimes it is possible, that the internet connection is slow or has some issues. If this fetching is running in the main thread of the app and has some issues, the GUI maybe blocked or freezed. That's why I outsourced it in an own thread. This decouples the solar data transfer from the main thread of the app and has no longer any influence on the GUI.

73 Heiko, DL1BZ