Optimized smooth lighting calculation code

src/main.cpp

@@ -167,6 +167,10 @@ TODO: Better control of draw_control.wanted_max_blocks
 TODO: Get player texture (and some others) from the specified texture
       directory
 
+SUGG: Simple light color information to air
+
+TODO: Block mesh generator to tile properly on smooth lighting
+
 Configuration:
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@@ -189,6 +193,8 @@ TODO: Don't update all meshes always on single node changes, but
 
 - Tool/weapon visualization
 
+FIXME: When disconnected to the menu, memory is not freed properly
+
 Server:
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