bzflag idle-sleep

void TimeKeeper::idleSleep(float seconds){  float dtime= idleTime - TimeKeeper::getCurrent();  if ((dtime < -1)||(dtime > 1)) {    idleTime= TimeKeeper::getCurrent();    idleTime.seconds -= 0.5;    // allow for some extra frames to catch up    return;  }  if (dtime > 0) {    TimeKeeper::sleep(dtime);  }  idleTime.seconds += seconds;}