Better let 'ViewerInterface' be part of the 'Okular' name space.

Also, use correct includes in 'viewerinterface.h'.

interfaces/viewerinterface.h

@@ -7,18 +7,23 @@
  *   (at your option) any later version.                                   *
  ***************************************************************************/
 
-#ifndef _VIEWERINTERFACE_H_
-#define _VIEWERINTERFACE_H_
+#ifndef _OKULAR_VIEWERINTERFACE_H_
+#define _OKULAR_VIEWERINTERFACE_H_
 
+#include "../core/okular_export.h"
+
+#include <QtCore/QObject>
 #include <QString>
 
+namespace Okular {
+
 /**
  * @short Abstract interface for controlling advanced features of a document viewer
  *
  * This interface can be used to control some more or less advanced features of a document
  * viewer.
  */
-class ViewerInterface
+class OKULAR_EXPORT ViewerInterface
 {
     public:
         virtual ~ViewerInterface() {}
@@ -43,6 +48,8 @@ class ViewerInterface
         void openSourceReference(const QString& absFileName, int line, int column);
 };
 
-Q_DECLARE_INTERFACE( ViewerInterface, "org.kde.viewerinterface/0.1" )
+}
+
+Q_DECLARE_INTERFACE( Okular::ViewerInterface, "org.kde.okular.ViewerInterface/0.1" )
 
 #endif

part.h

@@ -72,12 +72,12 @@ class ExportFormat;
  * @author Wilco Greven <greven@kde.org>
  * @version 0.2
  */
-class Part : public KParts::ReadOnlyPart, public Okular::DocumentObserver, public KDocumentViewer, public ViewerInterface
+class Part : public KParts::ReadOnlyPart, public Okular::DocumentObserver, public KDocumentViewer, public Okular::ViewerInterface
 {
     Q_OBJECT
     Q_CLASSINFO("D-Bus Interface", "org.kde.okular")
     Q_INTERFACES(KDocumentViewer)
-    Q_INTERFACES(ViewerInterface)
+    Q_INTERFACES(Okular::ViewerInterface)
 
     public:
         enum EmbedMode