remove dead code and fix changelog entry

CHANGELOG.md

@@ -12,7 +12,6 @@
     Bug #4602: Robert's Bodies: crash inside createInstance()
     Bug #4700: Editor: Incorrect command implementation
     Bug #4744: Invisible particles must still be processed
-    Bug #4752: UpdateCellCommand doesn't undo properly
     Bug #5088: Sky abruptly changes direction during certain weather transitions
     Bug #5100: Persuasion doesn't always clamp the resulting disposition
     Bug #5120: Scripted object spawning updates physics system

apps/openmw/mwrender/sky.hpp

@@ -32,17 +32,6 @@ namespace Resource
 
 namespace MWRender
 {
-    class AtmosphereUpdater;
-    class AtmosphereNightUpdater;
-    class CloudUpdater;
-    class Sun;
-    class Moon;
-    class RainCounter;
-    class RainShooter;
-    class RainFader;
-    class AlphaFader;
-    class UnderwaterSwitchCallback;
-
     ///@brief The SkyManager handles rendering of the sky domes, celestial bodies as well as other objects that need to be rendered
     /// relative to the camera (e.g. weather particle effects)
     class SkyManager

apps/openmw/mwrender/skyutil.cpp

@@ -278,10 +278,6 @@ namespace MWRender
             {
                 // no traverse
                 return;
-
-                osg::Vec4 v4;
-                osg::Vec4 v3;
-                v4 = v3;
             }
             else
             {