Clean up some warnings

Libs/DICOM/Core/ctkDICOMAbstractThumbnailGenerator.cpp

@@ -41,7 +41,7 @@ public:
 //------------------------------------------------------------------------------
 ctkDICOMAbstractThumbnailGeneratorPrivate::ctkDICOMAbstractThumbnailGeneratorPrivate(ctkDICOMAbstractThumbnailGenerator& o):q_ptr(&o)
 {
-
+    Q_UNUSED(o);
 }
 
 //------------------------------------------------------------------------------
@@ -55,7 +55,7 @@ ctkDICOMAbstractThumbnailGeneratorPrivate::~ctkDICOMAbstractThumbnailGeneratorPr
 ctkDICOMAbstractThumbnailGenerator::ctkDICOMAbstractThumbnailGenerator(QObject* parentValue)
   : d_ptr(new ctkDICOMAbstractThumbnailGeneratorPrivate(*this))
 {
-
+    Q_UNUSED(parentValue);
 }
 
 //------------------------------------------------------------------------------

Libs/DICOM/Core/ctkDICOMAbstractThumbnailGenerator.h

@@ -42,7 +42,7 @@ public:
   explicit ctkDICOMAbstractThumbnailGenerator(QObject* parent = 0);
   virtual ~ctkDICOMAbstractThumbnailGenerator();
 
-  virtual bool generateThumbnail(DicomImage* dcmImage, const QString& path ){return false;}
+  virtual bool generateThumbnail(DicomImage* dcmImage, const QString& path ) = 0;
 
 protected:
   QScopedPointer<ctkDICOMAbstractThumbnailGeneratorPrivate> d_ptr;

Libs/DICOM/Core/ctkDICOMDatabase.cpp

@@ -162,6 +162,7 @@ ctkDICOMDatabase::ctkDICOMDatabase(QString databaseFile)
 ctkDICOMDatabase::ctkDICOMDatabase(QObject* parent)
    : d_ptr(new ctkDICOMDatabasePrivate(*this))
 {
+    Q_UNUSED(parent);
     Q_D(ctkDICOMDatabase);
     d->registerCompressionLibraries();
 }