Add Continuous Mode (-r) to Run Train Continuously

[Umair-khurshid]

This pull request adds a new feature to the sl command, allowing the train animation to run continuously when the -c option is used.

Changes

• Added a new command-line option -r.
• Modified the main animation loop to run continuously if -r is specified.

Usage

To run the train continuously, use:
sl -r
To quit running the train, press:
q

Reason

This feature provides a fun way to keep the sl animation running without manual intervention.

Please review the changes and let me know if any adjustments are needed. Thank you!

[Umair-khurshid]

@mtoyoda Hi, can you please look into this?