There were several problems in the old random calculation:
* Different result in the viewport and render. * Noise "pop" in some frames. * Random number was calculated every time the file was opened, so get different results.
Now, instead to calculate the random numbers when n number of frames changed, the random values are calculated whith a seed by group of frames and stroke.
Also, a new Seed parameter has been added and this adds more control in the noise generated. This value can be animated and get more variations.
As result of these changes, some variables have been removed from Noise modifier struct too.