Zombie Fortress 0.5.6 Released

Another small patch.

Changes from 0.5.5 to 0.5.6:
- A debug fail-safe has been added to the event_start function. This should ensure the plugin will be always playable until I find out the reason why it gets skipped.
- Zombies no longer receive class information on spawn.
- The announcer should speak more properly when announcing 60 and 30 seconds remaining.