Different config files, multi-run and autostart

[webs1821]

Hello, for my purposes, to have internet from a different era on each of my computers, I modified the code and thought you might want to import some of it.

1. The main change is the abandonment of global variables and the use of a variable with a dictionary
2. Possibility to run the script with the -c config.json attribute. This allows you to have several configurations
3. config_handler now returns an object with the configuration that it loads from the given attribute or the default config.json file
4. I added the run_waybackproxy.sh file which runs three instances with sample configuration
5. The setup_waybackproxy_service.sh script creates a waybackproxy.service file that can be started by systemd at system startup