+u16 lighting_complete
+- Added in version 27.
+- This contains 12 flags, each of them corresponds to a direction.
+- Indicates if the light is correct at the sides of a map block.
+ Lighting may not be correct if the light changed, but a neighbor
+ block was not loaded at that time.
+ If these flags are false, Minetest will automatically recompute light
+ when both this block and its required neighbor are loaded.
+- The bit order is:
+ nothing, nothing, nothing, nothing,
+ night X-, night Y-, night Z-, night Z+, night Y+, night X+,
+ day X-, day Y-, day Z-, day Z+, day Y+, day X+.
+ Where 'day' is for the day light bank, 'night' is for the night
+ light bank.
+ The 'nothing' bits should be always set, as they will be used
+ to indicate if direct sunlight spreading is finished.
+- Example: if the block at (0, 0, 0) has
+ lighting_complete = 0b1111111111111110,
+ then Minetest will correct lighting in the day light bank when
+ the block at (1, 0, 0) is also loaded.
+