Parallellize `generate_scalpdata`

[arnevdk]

Nice simulation tool! I would like to use it, but long simulation times are holding me back a bit. Using a parallell for loop for generating epochs or components in generate_scalpdata can significantly speed up simulation.

[lrkrol]

Thanks for this excellent suggestion. I had not considered parallel processing before, but the switch turned out to be rather easy. The newly committed generate_scalpdata in the development branch should now make use of a parallel loop where available (additionally relying on utl_show_progress_timetocomplete and utl_show_progress_parfor to provide progress updates). Please let me know if this works for you!