Replay functionality, new icons

Yes, you can now view the last five games you played as a spectator! All I did was save each network packet that's sent out into a big list, then use Python's pickle module to serialize the list to a file. Each packet has a timestamp, so I just read the packets back in order, checking the timestamps to make sure it reads the packets back at the right speed. Fast forwarding is not implemented, but it would be pretty easy. Rewinding/seeking would be more difficult, so I'm not sure I'll get to implement those.

On the artistic side, here's a sample of the new icons! They're monotone so they can be tinted with the team color.