[Twisted-Python] Clean pb solution for two-way object sync?

[Daniel Sank]

> Here's my game that uses PB: https://github.com/dripton/Slugathon

This has been useful. I am learning from it and my own experimentation.

> One piece of advice: do the network code first and always exercise it, even
> when playing on a single computer.  Every time I've written a single-machine
> game first then tried to add networking later, the networking has been a
> mess to debug.

The way my classes are set up I can't run the game without the network
bits. Glad to hear this was good thinking.