Tal Hershkovich writes:
Edit your animation or mocap data quickly using a standard animation layers UI and workflow directly in your 3D viewport with the Animation Layers add-on.
A new update for Animation Layers V 0.5. Smart bake is now also working with cyclic Fcurves. Thanks to lucas cuenca for letting me have fun with his creature and testing on it. The Creature is rigged with Auto rig pro
Animation Layers is an addon that simplifies the work with the NLA Editor into a standard animation layers workflow. You can quickly select and edit each layer without the need to go into NLA's tweak mode, and always seeing the end result while working on any layer.
Add or Remove Layers quickly, or control their Influence using NLA's "Mute, Influence, Solo and its Blending modes" options.
When you are happy with your animation, you can always merge down your layers, which would bake all the layers from your current selected layer down to the Base layer.
If you want to keep the same amount of the overall keyframes after baking, then you can also use the smart bake option.
Reseting a pose and loading new actions automatically into the layers from the action editor
Why using animation layers? Luciano explained it pretty clearly