Merge pull request #97 from mrcdk/hdr_2d_fix

Fixes HDR for 2D demo

2d/hdr/beach_cave.tscn

@@ -6,7 +6,7 @@
 
 [sub_resource type="Environment" id=1]
 
-background_mode = 3
+background_mode = 4
 background_sky_custom_fov = 0.0
 background_color = Color( 0, 0, 0, 1 )
 background_energy = 1.0