Minecraft wiki entry for Development_versions, associated text: Light propagation now works correctly, fixing hostile mob spawning. (MCPE-49616)
Chunks should no longer fail to load properly in +250MB worlds. (MCPE-58514)
Fixed a bug with light persisting after a block change.
Ticking areas can no longer be removed on the same tick they are created (MCPE-36769).
Lighting now propagates correctly through chunk/subchunk borders (MCPE-58182).
Fixed an issue that could cause areas to show lighting errors on servers.
Added new overload for /replaceitem with an option for destroy (the old behavior) or keep (the command will return an error if an item occupies that slot).
The smooth camera option (from full keyboard gameplay) is no longer jittery and is smooth again (MCPE-54969).
The screen no longer twitches when the player dies in the Nether or End.