Many source file name and data type are prefixed by "skeleton" before, now all are refactored.
The class MeshResultContext represents the outcome of mesh generation before, now we have material, pose and animation, so we just rename it as Outcome.
This is the second version of auto-rig, differing from the first version, the user should pick up a rig type, unless no rig will be generated. Currently, only supports Tetrapod without tail. Export as glTF format to test this feature.
This commit also achive better quality quads than before.