MacGui: Acivity Logs for individual encodes initial implementation

MacGui: Acivity Logs for individual encodes initial implementation
- Individual activity logs are saved in the file format "YYYY-MM-DD HH-MM-SS mymoviename.txt".
- Default directory is "~/Library/Application Support/HandBrake/EncodeLogs/".
- Advanced preference available to alternatively put them in the users output movie directory with the output movie (by default set to "off").
- Renamed the existing contextual menu items for the Activity Window to better reflect choices (function remains the same) as follows:
-- "Copy All Output" -> "Copy Window Contents".
-- "Clear Output" -> "Clear Window Contents".
-- "Open Log File" -> "Open Log File For This Session".
-- "Clear Log File" -> "Clear Log File For This Session".
- Added "Open Individual Log File Directory" to the Activity Window contextual menu to open this directory with the Finder
- Also commented out some macgui based activity log messages that were used to troubleshoot the new queue.
- Note: the individual activity logs are in addition to the existing session based activity log. If you do a scan of a new source during encoding, the new source scan log messages will be intermixed with the encode log messages as I have no clue how to separate stderr/stdout based on which instance of libhb is sending the messages.

git-svn-id: svn://localhost/HandBrake/trunk@1881 b64f7644-9d1e-0410-96f1-a4d463321fa5