- Change runtime standalone detection:

* com_standalone now read-only
  * add new cvars com_basegame, com_homepath
  * standalone now automatically detected when com_basegame is set to something different than baseq3 and no id pak pk3s are found
  * This fixes https://bugzilla.icculus.org/show_bug.cgi?id=4699
- Replace a few hardcoded string literals with macros
- Add checks for Team Arena PK3s to FS_CheckPak0()

code/q3_ui/ui_menu.c

@@ -121,7 +121,7 @@ void Main_MenuEvent (void* ptr, int event) {
 		break;
 
 	case ID_TEAMARENA:
-		trap_Cvar_Set( "fs_game", "missionpack");
+		trap_Cvar_Set( "fs_game", BASETA);
 		trap_Cmd_ExecuteText( EXEC_APPEND, "vid_restart;" );
 		break;
 
@@ -248,7 +248,7 @@ static qboolean UI_TeamArenaExists( void ) {
 	for( i = 0; i < numdirs; i++ ) {
 		dirlen = strlen( dirptr ) + 1;
     descptr = dirptr + dirlen;
-		if (Q_stricmp(dirptr, "missionpack") == 0) {
+		if (Q_stricmp(dirptr, BASETA) == 0) {
 			return qtrue;
 		}
     dirptr += dirlen + strlen(descptr) + 1;