reset method
void
reset()
Removes every live particle and rewinds the clock (the seed stream and fractional spawn accumulator reset, so a restart replays identically).
prewarm is not replayed; a reset system starts empty at time zero.
Implementation
void reset() {
storage.clear();
spawner.reset();
_random = math.Random(seed);
_accumulator = 0.0;
_systemTime = 0.0;
}