With existing code if you pass a material instance with no parent in it will always default to the default surface material.
#codereview Martin.Mittring
[CL 2495685 by Nick Penwarden in Main branch]
#ttp 318670 - UE4: RENDERING: FORTNITE: Write HighResScreenshots to OpenEXR (ideally PSD as well)
#proj Engine
#branch UE4
#summary Added OpenEXR library, added OpenEXR format to ImageWrapper Module, Changed highres screenshot code to save with image wrapper.
#Add OpenEXR support (for writing) to ImageWrapper module. (enabled for windows builds only)
#Add added option to highres screenshot code to choose to output as hdr / openexr
#Add 2 new visualisation modes, scene depth world units and custom depth world units.
#add cvar 'r.BufferVisualizationDumpFramesAsHDR' to enable hdr export from console.
#change FRCPassPostProcessMaterial can specify an override output texture format if required.
#add SaveImage function to FHighResScreenshotConfig
[CL 2252882 by Allan Bentham in Main branch]
