centralize calls to make_zzword()

make_zzword() now called in set_seed(), because the only times it was
called in the entire application is after every invocation of set_seed().

main.c

@@ -141,8 +141,6 @@ static bool fallback_handler(char *buf)
         printf("Seed set to %ld\n", sv);
         // autogenerated, so don't charge user time for it.
         --game.turns;
-        // here we reconfigure any global game state that uses random numbers
-        make_zzword(game.zzword);
         return true;
     }
     return false;