Don't use ESM4::Lighting fog power as fog density

apps/openmw/mwworld/cell.cpp

@@ -24,7 +24,8 @@ namespace MWWorld
             .mAmbiantColor = cell.mLighting.ambient,
             .mDirectionalColor = cell.mLighting.directional,
             .mFogColor = cell.mLighting.fogColor,
-            .mFogDensity = cell.mLighting.fogPower,}
+            // TODO: use ESM4::Lighting fog parameters
+            .mFogDensity = 1.f,}
             ,mWaterHeight(cell.mWaterHeight)
     {
     }

components/esm4/lighting.hpp

@@ -33,7 +33,8 @@
 namespace ESM4
 {
 #pragma pack(push, 1)
-    // guesses only for TES4
+
+    // FO3/FNV version of the struct
     struct Lighting
     { //               | Aichan Prison values
         std::uint32_t ambient; //               | 16 17 19 00 (RGBA)
@@ -45,9 +46,10 @@ namespace ESM4
         std::int32_t rotationZ; // rotation z    | 00 00 00 00 = 0
         float fogDirFade; // Fog dir fade  | 00 00 80 3F = 1.f
         float fogClipDist; // Fog clip dist | 00 80 3B 45 = 3000.f
-        float fogPower = std::numeric_limits<float>::max();
+        float fogPower = 1.f; // TES4 doesn't have this
     };
 
+    // Currently unused
     struct Lighting_TES5
     {
         std::uint32_t ambient;