Synchronization for multi-person

[hunminkim98]

Hello, Dr. David,

I have modified the synchronization.py script to handle multi-person scenarios. I aimed to keep the modifications as clear and simple as possible, hopefully.

I have tested the script with the following cases:

• Demo
• A person who was initially detected but is no longer in the scene (and vice versa)
• A large number of people in the scene

Thank you for taking the time to read this!