Add magnet auto-configuration for HLT
Add back the code that is responsible for the magnet auto-configuration based on the currents in the configuration ptree when running online or in athenaHLT.py. Add a "Modifier" to enable the auto-configuration by default in testHLT_MT.py.
In addition, make sure the file input peeking is only done in athena.py
and not athenaHLT.py
.