Make result from plume analysis (_PlumeStats.df_) self-contained.

[andrejadd]

To get this include:

• substance name
• _plumethresh (also added to csv out table)
• panel$WellCoordsLengthUnit
• panel$rgUnits

This way I can ditch panel, substance, and _plumethresh from plot or saveCSV call.

Maybe add _groundporosity, which affects Plume Mass (but is not used inside plotPlumeTimeSeries()).