Remove #include <extensionsystem/pluginmanager.h> from icore.h, a

forward declaration is sufficient.

src/plugins/coreplugin/icore.h

@@ -35,36 +35,36 @@
 #define ICORE_H
 
 #include "core_global.h"
-#include <extensionsystem/pluginmanager.h>
 #include <QtCore/QObject>
-#include <QtCore/QList>
 
 QT_BEGIN_NAMESPACE
-class QSettings;
-class QStatusBar;
-class QFocusEvent;
 class QMainWindow;
 class QPrinter;
+class QSettings;
+template <class T> class QList;
 QT_END_NAMESPACE
 
+namespace ExtensionSystem {
+
+class PluginManager;
+
+} // namespace ExtensionSystem
+
 namespace Core {
 
-// forward declarations
 class ActionManager;
-class IFile;
-class FileManager;
-class MessageManager;
-class IEditor;
-class UniqueIDManager;
 class EditorManager;
+class FileManager;
+class IContext;
+class IWizard;
+class MessageManager;
+class MimeDatabase;
+class ModeManager;
 class ProgressManager;
 class ScriptManager;
+class UniqueIDManager;
 class VariableManager;
-class IContext;
 class VCSManager;
-class ModeManager;
-class IWizard;
-class MimeDatabase;
 
 class CORE_EXPORT ICore : public QObject
 {