anchor: love.joystick.saveGamepadMappings
  Saves the virtual gamepad mappings of all recognized as gamepads and have either been recently used or their gamepad bindings have been modified.
  
  The mappings are stored as a string for use with love.joystick.loadGamepadMappings.
  mappings = love.joystick.saveGamepadMappings( filename )
  filename string The filename to save the mappings string to.
  mappings string The mappings string that was written to the file.
  mappings = love.joystick.saveGamepadMappings()
  mappings string The mappings string.