TrkGeometry: Fix cppcheck warnings.

 - Prefer using an initializer list to assigning members
   in a ctor body.
 - Fix ctor/assignment deletion.
 - Missing member in assignment op.
 

Tracking/TrkDetDescr/TrkGeometry/TrkGeometry/TrackingVolume.h

@@ -410,10 +410,10 @@ namespace Trk {
       void moveTV ATLAS_NOT_THREAD_SAFE(Amg::Transform3D& transform) const;
            
       /** Forbidden copy constructor */   
-      TrackingVolume(const TrackingVolume&): Volume(), Material() {} 
+      TrackingVolume(const TrackingVolume&) = delete;
 
       /** Forbid assignment. */
-      TrackingVolume &operator=(const TrackingVolume&) { return *this; }
+      TrackingVolume &operator=(const TrackingVolume&) = delete;
        
       const TrackingVolume*        m_motherVolume;  //!< mother volume of this volume
 

Tracking/TrkDetDescr/TrkGeometry/src/CompoundLayerMaterial.cxx

@@ -13,9 +13,9 @@ Trk::CompoundLayerMaterial::CompoundLayerMaterial() :
   Trk::LayerMaterialProperties(),
   m_materialProperties(new Trk::MaterialProperties()),
   m_binUtility(nullptr),
-  m_fullComposition(false)
+  m_fullComposition(false),
+  m_elementTable (Trk::SharedObject<const Trk::ElementTable>(nullptr))
 {
-    m_elementTable = Trk::SharedObject<const Trk::ElementTable>(nullptr);
 }
 
 Trk::CompoundLayerMaterial::CompoundLayerMaterial(const Trk::BinUtility& binutility,

Tracking/TrkDetDescr/TrkGeometry/src/Layer.cxx

@@ -118,6 +118,7 @@ Trk::Layer& Trk::Layer::operator=(const Trk::Layer& lay)
   if (this != &lay){
     delete m_overlapDescriptor;
     delete m_surfaceArray;
+    m_layerThickness                    = lay.m_layerThickness;
     m_enclosingTrackingVolume           = lay.m_enclosingTrackingVolume;
     m_enclosingDetachedTrackingVolume   = lay.m_enclosingDetachedTrackingVolume;
     m_overlapDescriptor                 = (lay.m_overlapDescriptor) ? lay.m_overlapDescriptor->clone() : nullptr;