Inform dashboard about token changes in a Petri Net in a lightweight format

[OliverStolzBO]

Since Petri Net updates often only consist of changing the token labels of single nodes, it is not necessary to resend the whole dotfile every time to update the SWAP-IT dashboard. Instead, the dotfile should only be resent in the case of major changes in the graph (such as node movement or addition). In the case of token updates only, it would be sufficient to send the node IDs whose token has been updated (added or removed). This would improve the performance of the dashboard and reduce network traffic.