Move music tracks out of akgl_Game to make it more suitable for serialization

src/game.c

@@ -23,8 +23,8 @@ akgl_Frame paddle2;
 akgl_Frame table;
 akgl_Tilemap gamemap;
 MIX_Audio *bgm = NULL;
-MIX_Mixer *GAME_mixer = NULL;
-MIX_Track *GAME_tracks[64];
+MIX_Mixer *akgl_mixer = NULL;
+MIX_Track *akgl_tracks[AKGL_GAME_AUDIO_MAX_TRACKS];
 SDL_FRect camera;
 akgl_Game game;
 
@@ -86,10 +86,10 @@ akerr_ErrorContext AKERR_NOIGNORE *akgl_game_init()
 	AKGL_ERR_SDL,
 	"Couldn't initialize audio: %s",
 	SDL_GetError());
-    game.mixer = MIX_CreateMixerDevice(SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK, 0);
+    akgl_mixer = MIX_CreateMixerDevice(SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK, 0);
     FAIL_ZERO_RETURN(
 	errctx,
-	game.mixer,
+	akgl_mixer,
 	AKGL_ERR_SDL,
 	"Unable to create mixer device: %s",
 	SDL_GetError());
@@ -134,6 +134,27 @@ akerr_ErrorContext AKERR_NOIGNORE *akgl_game_save(char *fpath)
 
 akerr_ErrorContext AKERR_NOIGNORE *akgl_game_load(char *fpath)
 {
+    FILE *fp = NULL;
+    char version[32];
+    
     PREPARE_ERROR(errctx);
+    FAIL_ZERO_RETURN(errctx, fpath, AKERR_NULLPOINTER, "NULL file path");
+    fp = fopen(fpath, "rb");
+    FAIL_ZERO_RETURN(
+	errctx,
+	(fread((void *)&version, 1, 32, fp) < 32),
+	AKERR_IO,
+	"Corrupt save file");
+    FAIL_ZERO_RETURN(
+	errctx,
+	strncmp((char *)&game.version, (char *)&version, 32),
+	AKERR_API,
+	"Save game can not be loaded, it is from an incompatible version");
+    rewind(fp);
+    FAIL_ZERO_RETURN(
+	errctx,
+	(fread((void *)&game, 1, sizeof(akgl_Game), fp) < sizeof(akgl_Game)),
+	AKERR_IO,
+	"Corrupt save file");
     SUCCEED(errctx);
 }