osx: Command-line parameter control

* Now the "Eternity Engine" launcher can receive command-line parameters, by using the "open -a 'eternity engine' --args ..." shell command. If so, it will launch the game from startup and self-quit when done. This will allow remote-controlling Eternity launches from shell.
* Fixed a minor memory leak
* Reimplemented safe Application Support folder detection, correctly.
* Clean up stuff
Style change only
Fix menu savegame name reading problem

Also, use secure qstring to do menu input buffering.
Merge branch 'master' of https://github.com/team-eternity/eternity
Merge branch 'master' into AutoDoom