Improves detection of Explorer being the default shell.
- Check the "Software\Microsoft\Windows NT\CurrentVersion\Winlogon" key to see if Explorer is the default shell.
- Use this check to determine whether to start the desktop and taskbar or only open a file browser window.
JIRA issue CORE-19887
- Rewrite the taskbar settings and start menu settings property sheets.
- All settings in the taskbar settings property sheet can be loaded and saved properly except for the quick launch one which will be implemented later.
- Implement toggling lock, autohide and always on top. The rest will be implemented later.