Remove the GLES skybox fix as it was doing more harm than good. Closes #1011.

bin/CoreData/Shaders/GLSL/Skybox.glsl

@@ -9,13 +9,7 @@ void VS()
     mat4 modelMatrix = iModelMatrix;
     vec3 worldPos = GetWorldPos(modelMatrix);
     gl_Position = GetClipPos(worldPos);
-
-    #ifndef GL_ES
     gl_Position.z = gl_Position.w;
-    #else
-    // On OpenGL ES force Z slightly in front of far plane to avoid clipping artifacts due to inaccuracy
-    gl_Position.z = 0.999 * gl_Position.w;
-    #endif
     vTexCoord = iPos.xyz;
 }