Takes a well formed, fully parsed pack file object and adds its entries into the load queue. Usually you do not call
this method directly, but instead use
Loader.pack and supply a path to a JSON file that holds the
pack data. However, if you've got the data prepared you can pass it to this method.
You can also provide an optional key. If you do then it will only add the entries from that part of the pack into
to the load queue. If not specified it will add all entries it finds. For more details about the pack file format
The Pack File data to be parsed and each entry of it to added to the load queue.
An optional key to use from the pack file data.
true if any files were added to the queue, otherwise