This removes the dependency of the Havok SDK or getting the decompiled
skeleton files from TexTools or some other place. Code courtesy of
FFXIVTools. The other two ways of reading skeletons (SKEL and Packfile)
are removed which gets rid of two dependencies.
Now we support TexTools skel files, alongside the usual Havok packfiles.
Neither one has complete support (yet) but I'm exploring libraries to
accomplish them.
The dependencies are now commented to describe their usage and future
plans.