Fix double to float cast warnings in the RGBE plugin.
Fix double to float cast warnings in the RGBE plugin.

OpenImageIO/oiio,OpenImageIO/oiio,cwilling/oiio,sambler/oiio,lgritz/oiio,cwilling/oiio,OpenImageIO/oiio,lgritz/oiio,cwilling/oiio,bdeluca/oiio,scott-wilson/oiio,YangYangTL/oiio,OpenImageIO/oiio,micler/oiio,YangYangTL/oiio,lgritz/oiio,cwilling/oiio,mcanthony/oiio,scott-wilson/oiio,scott-wilson/oiio,micler/oiio,scott-wilson/oiio,YangYangTL/oiio,micler/oiio,mcanthony/oiio,bdeluca/oiio,sambler/oiio,sambler/oiio,lgritz/oiio,mcanthony/oiio,sambler/oiio,bdeluca/oiio,bdeluca/oiio,YangYangTL/oiio,mcanthony/oiio,micler/oiio