Bugfix for SoftKiller application to PFlow

Evidently the IgnoreChargedPFO property was accomplishing exactly the opposite, probably because in the past the logic was "reject" rather than "accept". This would have meant the SK min pt would have been calculated from charged PFOs rather than neutrals as was intended.

Includes other sundry fixes, mainly for dual use code.

FYI, @jroloff, @delsart, @jkinghor, @mleblanc