Added Zero Checking prior to decrementing the currentNodeIndex.

This change prevents the node index from going negative and will allow
execution to continue instead of a hardware exception which stops the
output controller.
Reuse the collection to reduce object creation. Method is called for every state update.
Merge remote-tracking branch 'remotes/komby/master'
Merge remote-tracking branch 'remotes/jeffu231/master'
Merge Bill's fixes for the Nutcracker 'backwards megatree' issue (merging his and Derek's work). Still has debugging stuff enabled.
Remove some debugging messages from the nutcracker effect.
Avoid crash when playing a sequence if the mp3 file is missing.  This change allows Giz's sequence to play even though I don't have his audio file.
Merge remote-tracking branch 'upstream/master'