Minecraft wiki entry for Development_versions, associated text: Players without scripting enabled now see an appropriate message if they try and join an incompatible server that has scripting enabled.
Updating a player's position with scripting now correctly syncs with the player.
Creating actors via script now avoids the spawning logic.
This prevents hard-coded logic like ocelots spawning along with baby ocelots.
Improved the message wording for players who get disconnected due to unsupported scripts.
Allow events to fire without a defined event data object.
Renaming Views to Actor/Entity Queries.
Added sound events to the scripting API.
Add Event Data to load_ui.
Custom UIs can now be made like regular in-game UI screens.
Added 'Global Objects' to the scripting API.
Refactored JavaScript object registration.
Added the ability to enable and disable scripting error and warning logging.