Add explicit --save_state_filename to offline node options. (#1204)
Add explicit --save_state_filename to offline node options. (#1204)

This allows to serialize the state also when no bagfile is given, e.g.
when the offline node is used to run an optimization and/or trimming
configuration on a pbstream. Or simply when one wants to use a custom
name directly. This doesn't break compatibility with the previous CLI.
cartographer-project/cartographer_ros,cartographer-project/cartographer_ros,wohe/cartographer_ros,wohe/cartographer_ros,googlecartographer/cartographer_ros,googlecartographer/cartographer_ros,cartographer-project/cartographer_ros,wohe/cartographer_ros,googlecartographer/cartographer_ros