Fix memory leak in mitkImageVtkMapper2DLevelWindow unit test

Signed-off-by: Taylor Braun-Jones <taylor.braun-jones@ge.com>
Fix memory leaks in VtkPropRenderer::Initialize2DvtkCamera

Signed-off-by: Taylor Braun-Jones <taylor.braun-jones@ge.com>
Merge branch 'bug-18017-RestructurePlaneGeometryTest'
replace delay by forceImmediateUpdate
COMP: Removed unused Variable
Merge branch 'bug-18017-RestructurePlaneGeometryTest'
Merge branch 'bug-18083-AddDelayAfterRenderInRenderingTestHelper'
removed unnecessary check that prevented multiframe support
Merge branch 'bug-18085-dicom-multiframesupport-master'
Merge branch 'bug-16674-fix-memory-leaks-SurfaceToImageFilter'
Merge branch 'bug-16674-fix-memory-leaks-VtkPropRenderer'
Merge branch 'bug-16674-fix-memory-leaks-ImageVtkMapper2DLevelWindowTest'
Added missing return statement.
Merge branch 'bug-18086-fix-messagebase-assignment-operator'

* bug-18086-fix-messagebase-assignment-operator:
  Added missing return statement.
Merge branch 'master' into bug-15899-ImageVtkMapper2DIgnoresOpacityIntegration

Conflicts:
	Core/Code/Rendering/vtkMitkLevelWindowFilter.cpp
	Core/Code/Rendering/vtkMitkLevelWindowFilter.h
	Core/Code/Testing/CMakeLists.txt
Added scalar opacity transfer function test data.
Merge branch 'bug-15899-ImageVtkMapper2DIgnoresOpacityIntegration'
Merge branch 'bug-15912-QmitkTransferFunctionWidgetLacksRendererSpecificTransferFunctionAbility'

Conflicts:
	Modules/QmitkExt/QmitkTransferFunctionWidget.cpp
	Modules/QmitkExt/QmitkTransferFunctionWidget.h
Merge branch 'bug-15913-TransferFunctionWidgetsDoNotDisplayAllDigits'

Conflicts:
	Modules/QtWidgetsExt/QmitkColorTransferFunctionCanvas.cpp
	Modules/QtWidgetsExt/QmitkPiecewiseFunctionCanvas.cpp
	Modules/QtWidgetsExt/QmitkTransferFunctionWidget.ui
Merge branch 'bug-16028-DataNode-const-correct-params'

Conflicts:
	Core/Code/DataManagement/mitkDataNode.cpp
	Core/Code/DataManagement/mitkDataNode.h
	Core/Code/DataManagement/mitkDataStorage.cpp
	Core/Code/DataManagement/mitkDataStorage.h