Adds a new python class and new functions to support converting objects to a
PSet (parameter set) or a VPSet (vector of PSets). This is needed for the new
mixing feature for premixed pileup stored as raw data. This tag has been
tested. All relvals pass. It just adds new python code, which is currently
unused.
Merge pull request #24 from ktf/tagset-133204

Adds a new python class and new functions to support converting objects ...