Can't have different nseqparts for each beam

[mightylorenzo]

Currently, when Puffin loads the beam it uses the same number of particles in the pseudo-random sequences for each slice for each beam. This is not as described in the manual, and should be able to be set independently for each beam.

If more than one beam is used, and more than one value is given for nseqparts, Puffin crashes.