Implement NPC spawning.

Protected by a simplified GM system. Either everyone is a GM (local
servers) or nobody is (public servers).

config.ini

@@ -25,6 +25,8 @@ motd=Welcome to OpenFusion!
 npcdata=NPCs.json
 # warp target json data
 warpdata=warps.json
+# is everyone a GM?
+gm=true
 
 # spawn coordinates (Z is height)
 # the supplied defaults are at City Hall