Garry's Mod JukeBox - YouTube Music Player

1. Added setting JukeBox.Settings.RestrictMenu
2. Can be used alongside JukeBox.Settings.UseGroupRestrictions to prevent the menu being openable by restricted groups.
3. Added language phrase #CHAT_CantOpenMenu

There have been changes to the shared_settings.lua and shared_language.lua files, so be sure to copy over your settings carefully.