when cloning a particle set LastMother to -1 in case source had two mothers

[nusense]

do this at the same point where FirstMother is set to the original particle

[sjgardiner]

Looks great @nusense, just a couple of questions for you.

[sjgardiner]

Do you understand the intended behavior of the int mom argument here? This seems unique to hN. All non-hN revisions look fine.

[sjgardiner]

This is the other place that's questionable, for the same reason.

[nusense]

From slack discussion:
@sjgardiner All looks good, except I don't understand the hN recipe. What you have is probably OK there too, though.
@nusense
Hmm.  No I don't really understand the original logic of it.   I think what's happening is there's split in the functionality between the cloning of the particle and the actual filling out the new particle (passed into the method).