WPF: Several bug fixes, added images for toolbar shuffle/repeat states, added tray icon.

- The tray icon hides/shows the app but there is no contextual menu for
now.
- Several visual and functional bug fixes in PreferencesWindow
(checkboxes did not use the Unchecked event, layout bug fixes, color bug
fixes, peak folder size was not displayed, etc.)
- Revised main menu in MainWindow
- Changed fonts in SyncWebBrowserWindow.
- Fixed build on Android.