(svn r1389) -Add: [Network] Added packet protection. No longer a client or server

reads beyond the size of the packet
-Fix: [Network] A server no longer crashes when a client sends an 
invalid DoCommand, but drops the client instead.

command.h

@@ -182,6 +182,7 @@ enum {
 int32 DoCommand(int x, int y, uint32 p1, uint32 p2, uint32 flags, uint procc);
 int32 DoCommandByTile(TileIndex tile, uint32 p1, uint32 p2, uint32 flags, uint procc);
 
+bool IsValidCommand(int cmd);
 int32 GetAvailableMoneyForCommand();
 
 #endif /* COMMAND_H */