Upgrades to Xcode project and Apple Silicon support

- Reorganized Xcode project
- Added missionpack support to Xcode project
- Incorporated changes from MaddTheSane for Apple Silicon support https://github.com/maddthesane/ioq3
- Built SDL 2.0.14 for Apple Siicon, added to existing SDL dylib
- Built SDLMain for Apple Silicon, added to existing libSDL2main.a

misc/xcode/xcode-readme.txt

@@ -26,7 +26,6 @@ LIBRARIES:
 
 TODO:
 - dedicated support
-- missionpack support
 - curl.xcodeproj
 - ogg.xcodeproj (ogg vorbis support)
 - zlib.xcodeproj
@@ -47,5 +46,6 @@ TODO:
 
 
 
+
 NO CARRIER