Improve OS notifications for Windows

[djing-chan]

For Windows we use AwtNotifications. The current implementation does not looking nice (on Ubuntu when disabling the Linux notifications, not tested on Windows). For Linux system where ``notify-send` is not supported, it also falls back to AwtNotifications.

There are some libraries for JavaFX notification implementations which could be considered to be used as fallback or alternative to AWT: https://github.com/PlusHaze/TrayNotification https://github.com/dustinkredmond/FXTrayIcon https://github.com/controlsfx/controlsfx https://gist.github.com/wiverson/d2edf0d66ad195c96793d0d25290753b

A native Windows notification solution would be preferred.