User: Possible temporary online physics class

Untested with online running! This is a totally paired down version
of what anyone would actually like to use (not much available from
TA2Calorimeter besides p4...). Current analysis of 2 particle,
3 particle, and 6 particle case is included. However no partID from
TA2Calorimeter, so can't be sure that you're not including charged
stuff... Will push something better for online running later.