diskmanager: clearing disk cache at runtime will correctly signal renderers

Clearing the disk cache in the preferences will correctly communicate to
renderers that those frames are now deleted.

app/render/diskmanager.h

@@ -20,7 +20,7 @@ public:
 
   void CreatedFile(const QString& file_name, const QByteArray& hash);
 
-  bool ClearDiskCache();
+  bool ClearDiskCache(bool quick_delete);
 
 signals:
   void DeletedFrame(const QByteArray& hash);