Added functions to extract Havok pak files, and extract some skeleton
data from an externally processed Havok XML file. This still requires
you to use the proprietary Havok SDK though, but I'll think of a
solution in the future.
Now you can easily parse EXL files, and this commit includes changes
to GameData to easily extract a EXH from just an excel sheet name
like "Item" or "Map". However this still doesn't work for language
seperated excel sheets yet.
