getCommandLifetime returns the current command lifetime [s].
 
    This method provides a way to programmatically access 
    the current command lifetime.
 
    The command lifetime is the duration for which a sent 
    command remains active. If the hardware does not receive
    further commands within the specified time frame, all local
    controllers get deactivated. This is a safety feature
    to mitigate the risk of accidents in case programs get
    interrupted in an unsafe state, e.g., on user interrupts
    (ctrl+c) or during a network fault.
 
    Additionally, supporting hardware does not accept commands
    from any other sources during the lifetime of a command.
    This mitigates the risk of other users accidentally sending
    conflicting targets from, e.g., the GUI, or any other groups
    running in Matlab or from any other APIs.
 
    The default command lifetime for a new group is 0.25 sec.