Merge branch 'shadows' into 'master'

Data/IBL/roomBRDF.png.sha512

Data/IBL/roomIrradiance.dds.sha512

Data/IBL/roomRadiance.dds.sha512

Examples/Sandbox/CMakeLists.txt

Examples/Sandbox/main.cpp

Source/Core/imstkColor.cpp

Source/Materials/imstkRenderMaterial.cpp

Source/Materials/imstkRenderMaterial.h

Source/Materials/imstkTexture.h

Source/Rendering/VTKRenderer/VTKShaders/mesh.frag

...ce/Rendering/VTKRenderer/imstkVTKCustomPolyDataMapper.cpp

.../VulkanRenderer/PostProcessing/imstkVulkanPostProcess.cpp

...ng/VulkanRenderer/PostProcessing/imstkVulkanPostProcess.h

...enderer/PostProcessing/imstkVulkanPostProcessingChain.cpp

...nRenderer/PostProcessing/imstkVulkanPostProcessingChain.h

...derer/RenderDelegate/imstkVulkanCapsuleRenderDelegate.cpp

...enderer/RenderDelegate/imstkVulkanCapsuleRenderDelegate.h

...Renderer/RenderDelegate/imstkVulkanCubeRenderDelegate.cpp

...anRenderer/RenderDelegate/imstkVulkanCubeRenderDelegate.h

...enderer/RenderDelegate/imstkVulkanDecalRenderDelegate.cpp