Remove unused hdr framebuffer and texture

include/openspace/rendering/framebufferrenderer.h

@@ -191,11 +191,6 @@ private:
         GLuint colorTexture[2];
     } _pingPongBuffers;
 
-    struct {
-        GLuint hdrFilteringFramebuffer;
-        GLuint hdrFilteringTexture;
-    } _hdrBuffers;
-
     struct {
         GLuint fxaaFramebuffer;
         GLuint fxaaTexture;