Managing multiple skeleton poses (model pose, T pose etc.)

Usually the skeleton will be built for a mesh in a model pose and this is also the position that the mesh will be skinned in. For constructing control rigs however, we want the skeleton in a T pose.

Also, character models are frequently updated after the rig is created and functionality can change which require modifications or additions to the skeletal hierarchy. All these modifications need to happen with the skeleton in the original bind pose, so the ability to store and apply multiple poses for both creation and ongoing maintenance of character rigs is essential.