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.
Shortcuts implementation now use QShortcut instead of using the raw key event.
Besides, hold spacebar to temporarily enter drag mode also implemented in this commit, this is very useful in zoom mode.
Jeremy Hu