Fixed update bug in previous commit

Apparently, having SwingUtilities manage the GUI updating caused a NullPointerException to be thrown when trying to access the JAR file when it was rewritten. In other words, the automatic updating broke. People will need to manually redownload the newest version, and then updating will work.

-Fixed updating issue in previous commit
-Made JAR download to temp JAR, then copy to current JAR and delete temp
-Added auto-running of latest version after updating
-Added unused daemon Thread creation method
-Renamed some variables to make them clearer