- corrected transferred sky offsets using ZDoom 2.8.1 source - the sk…

…y needed to be offset by 28 units.

src/swrenderer/plane/r_skyplane.cpp

@@ -139,7 +139,7 @@ namespace swrenderer
 				skyangle += FLOAT2FIXED(s->GetTextureXOffset(pos));
 
 				// Vertical offset allows careful sky positioning.
-				skymid = s->GetTextureYOffset(pos);
+				skymid = s->GetTextureYOffset(pos) - 28.0;
 
 				// We sometimes flip the picture horizontally.
 				//