(svn r1711) - Add: [MacOSX] Added an Xcode project file (Tobin)

This project file adds a graphical IDE to OSX, including graphical debugging, which is a bit easier than gdb (Xcode uses gdb for debugging)
Since it uses the makefile to compile, it should (hopefully) work without updating the project file when the makefile is updated
Tobin did most of the work, but I altered paths and settings for custom executable so it should work out of the box for everybody

#ifndef NETWORK_LAN_H
#define NETWORK_LAN_H

#ifdef ENABLE_NETWORK

void NetworkUDPInitialize(void);
bool NetworkUDPListen(SOCKET *udp, uint32 host, uint16 port, bool broadcast);
void NetworkUDPReceive(SOCKET udp);
void NetworkUDPSearchGame(void);
void NetworkUDPQueryMasterServer(void);
NetworkGameList *NetworkUDPQueryServer(const byte* host, unsigned short port);
void NetworkUDPAdvertise(void);
void NetworkUDPRemoveAdvertise(void);

#endif

#endif /* NETWORK_LAN_H */