Improving Brownian noise

[rdinse]

The Brownian noise sounds better when the random walk is reflected at the boundaries like this:

    double brown = _lastBrownSample;

    for (i = 0; i < bufferFrames; i++) {
        double white = ((long)sGetNextRandomNumber()) * (double)(1.0f / LONG_MAX);
        brown += white;

        if (brown > 32.0) brown -= brown - 32.0;
        if (brown < -32.0) brown -= brown + 32.0;

        sample = (float)brown * 0.03125 * _volume;
        *buffer++ = sample;
    }

    _lastBrownSample = brown;

I've also added a new member variable which stores the last sample so that the transition is always seamless. Currently, there are occasionally subtle click noises when the difference between the first and last sample happen to be large.