• engine: Luminance scaling can now be used with any tone mapping operator. It was previously tied
  to the "EVILS" tone mapping operator.
• engine: Removed the "EVILS" tone mapping operator [⚠️ API Change].
• engine: Improvements to Skinning. A new SkinningBuffer API allows bone sharing between
  renderables.
• engine: Improvements to internal memory allocation for Metal and Vulkan backends.
• engine: Default to OpenGL backend when Windows does not support Vulkan.
• samples: Add new sample app: image_viewer.