move from EventInfo to xAOD::EventInfo; retrieve HltResult

- use the conversion tool to get xAOD::EventInfo from the old EventInfo
and use the xAOD one throughout the EventLoopMgr
- perhaps the L1 trigger bits still need to be retrieved somehow for the final
result building
- retrieve the HltResult from event store after processing (not really used yet)
- also change the message format for clarity with nthreads>1