World config to server config.

[timriker]

World config defaults should move closer to BZFlag and be configurable in server.json

This should include at least:

• tank linear/angular speeds limits (-a)
• gravity
• jump velocity
• shot speed
• shot duration
• maxshots (-ms)
• max players (-mp existing)
• port number (-p existing)
• time of day? (how fast time progresses and what time to start with)
• map (-world existing)

More should be added as we add flags, teams, game modes, etc.