As best practice, always define which version of the viewer you want your application to use. Do this in order to avoid any breaking changes and you can test functionality in your dev environment before moving to a new version.

CHANGES

three.min.js and three.js are no longer required. These libraries are now bundled into viewer3D.min.js and viewer3D.js respectively.
Improved display and sizing of Settings Panel
Reflectivity is reduced at grazing angles in phong shader for some Protein materials.
Can now zoom more than 100% in PNG/JPG image files
default value is now false for applyRefPoint option
Replaced Autodesk.Viewing.theHotkeyManager with viewer.getHotkeyManager()
Replaced HotkeyManager.KEYCODES with Autodesk.Viewing.KeyCode
IFC tranlsations are treated as AEC models

ADDED

Added monochrome mode for 2D models: viewer.setGrayscale(true)
Added AEC Extension
- This submission is an initial file dump, and adaptation will be needed to SectionTool and BlendShader to make the extensions fully functional.
- It also shows how to build an LMV extension using modern JavaScript and package it with webpack.

Added version to Settings Panel, bottom right
Adding various cross-fade logic used by view transitions
Added option to disable node box caching
Added preference value wheelSetsPivot along with Navigation methods
Added edge color/opacity for ghosted shapes
Add spatial filter support to RenderContext and blend_frag.glsl
Localization strings for recently added IBLs and for Scalaris extension
Expose config3d.modelBrowserExcludeRoot to configure whether the Model Browser will display the model's root node or not (default is to not display it)
Expose config3d.modelBrowserStartCollapsed to configure whether the Model Browser will have the topmost node collapsed or not (default is no, aka: expanded)

FIXED

A360 Preview tab images are now loaded
Pressing the ESC key in the LMV window no longer confuses which state the icons are in
Choosing specific environments now forces "Environment Image Visible" to enabled or disabled
After enabling the zoom tool holding the ALT key now enables the orbit tool as expected
Property Panel now shows the root-node properties when nothing is selected.
Search is no longer shown for PDF bubble
Selected object is now highlighted properly
2D and 3D selection color settings are decoupled
Fixed loading problem with models that use memory optimized mode
Fixed loading problem with Animation extension
Prevent renaming window.name to "user_info"
Screen is no longer temporarily black at startup
Fixed missing highlight