Exaile 4.0.0-rc0 released

[Dustin Spicuzza]

This release comes highly recommended with a slew of minor fixes including:

• Add preference to tell Gtk to use dark theme
• Drag and drop fixes
• Use Gst.DeviceMonitor on Windows

See https://github.com/exaile/exaile/releases for the latest releases. We expect to do a final 4.0 release shortly!