MacGui: End of encode/queue alerts and actions changes

MacGui: End of encode/queue alerts and actions changes
- Growl alerts and "Send to MetaX" actions occur as each encode comes finishes in the queue.
- The standard alert window, computer sleep and computer shutdown all occur at the end of encoding the entire queue, specifically when the encoding is done, and there aren't any other pending encodes to process.

git-svn-id: svn://localhost/HandBrake/trunk@1739 b64f7644-9d1e-0410-96f1-a4d463321fa5