Made the ROS wrappers as a separate library to fix linking issues and improve the modularity of the code.

Fixing some bugs here and here, added a new method to track objects with variable dt in Track2D, and reanabled the standalone classes.

renamed the file to something more meaningful. Now compiling all the way but there is a linking issue.

Fixed the const issue in the std::map. For a reason, std::map does not accept element.first as a key, instead, I had to use the at function.