Mac OS X work...lots of little changes that touch a lot of random places.

Still work to be done, but this at least matches the PowerPC Linux status
 now.

MacOS-specific directory (and XCode project) is gone...this now uses SDL,
 OpenAL, and the Unix Makefiles.

--ryan.

code/unix/unix_glw.h

@@ -19,7 +19,7 @@ along with Quake III Arena source code; if not, write to the Free Software
 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 ===========================================================================
 */
-#if !( defined __linux__ || defined __FreeBSD__ || defined __sun)
+#if !( defined __linux__ || defined __FreeBSD__ || defined __sun || defined MACOS_X )
 #error You should include this file only on Linux/FreeBSD/Solaris platforms
 #endif