Allow access to system scope setting.

This commit add a Settings::Scope parameter to
Core::ICore::settings(), the default is UserScope,
which falls back to SystemScope. Specifying SystemScope
instead gives exclusive access to the SystemScope.

src/plugins/coreplugin/coreimpl.cpp

@@ -31,6 +31,7 @@
 
 #include <QtCore/QDir>
 #include <QtCore/QCoreApplication>
+#include <QtCore/QSettings>
 
 namespace Core {
 namespace Internal {
@@ -135,9 +136,9 @@ MimeDatabase *CoreImpl::mimeDatabase() const
     return m_mainwindow->mimeDatabase();
 }
 
-QSettings *CoreImpl::settings() const
+QSettings *CoreImpl::settings(QSettings::Scope scope) const
 {
-    return m_mainwindow->settings();
+    return m_mainwindow->settings(scope);
 }
 
 SettingsDatabase *CoreImpl::settingsDatabase() const