整体效能改善部分：
Terrain: Normal map & custom shader support for Terrain. Added built-in shader Nature/Terrain/Bumped Specular; added "normal map" texture slot to terrain splat maps; added Material field under terrain settings.
Graphics: Added GL.wireframe script API.
Graphics: shader properties can have [HideInInspector] in front of them, which makes them hidden in inspector (useful for properties that are set from code).
Editor: Inspector Window recovers gracefully when a CustomEditor throws an exception or has missing layout group endings.
Project Browser: Enable searching the asset store and previewing assets.
Flash: Full support for animation events, including***ntime scripting api.
Profiler : Made profiler player connection***n threaded to improve throughput and reduce lack on profile data.
Font rendering: Add Font.RequestCharactersInTexture, Font.GetCharacterInfo and Font.textureRebuildCallback to allow full control over dynamic fonts from scripting.
Cache Server: Made Editor no longer connect to cache server when it's not needed.
Mac OS X Standalone: Added support for 256x256, 512x512 and 1024x1024 icons.
Changes
Editor: When in OpenGL ES 1.1 graphics emulation, maximum texture size increased from 1024 to 2048 now.
iOS: SystemInfo.deviceModel now returns full device name, including revision number.
iOS: exposed AOT.MonoPInvokeCallbackAttribute custom attribute. Passing managed delegates to native functions is now possible, though limited to static methods only.
修复的功能：
Editor: Fixed prefab override recording issue where modifications would not get applied to array elements if the prefab array is empty and the size value was overridden after the property was overridden.
Editor: Fixed warning when changing import settings on a lot of fbx files.
Editor: Fixed crashbug when clicking on Apply prefab button in the game object inspector when the prefab would add / remove components on awake in edit mode.
Editor: Fixed drag and drop behaviour when dragging child prefab objects.
Editor: Improvements to Light Probe editing: don't change selection when duplicating them; render editable ones on top of baked ones; fixed probe visualization on DX11.
Editor: Wireframe and Textured Wireframe scene view modes take actual vertex & tessellation shaders into account now.
Editor: Fixed import of .EXR files with alpha channel.
Editor: Invoked OnFocus/OnLostFocus when switching tabs within the same DockArea.
Editor: Disallowed hiding cursor when GameView is out of focus.
Editor: Fixed crash caused by scene view overlays.
Editor: Fixed box collider handles not matching box collider gizmos.
Editor: Text fields support OS standard behavior of Command + Backspace deleting everything from the start of the current line to the cursor position.
Editor: Cleaned up LOD group inspector (button alignment, text clipping).
Editor: Make Unity 1.x GUI components never be shown in the Scene View.
