Add a crc64 hash check for history keeping to avoid repeated snapshot.
Besides, before, there is a logic error in the undo implementation, which recover the most recent snapshot from undo stack, so user need undo twice and at the second undo get the expected result. This incorrect behavior got fixed.
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.
Jeremy Hu