reading event id from EVM FED

Hi,
These are changes/bugfixes from MWGR3:
* reading 32 bit event ID from GTP (EVM) FED. useL1EventID parameter is provided for switching back to 24-bit ID (if there are problems with runs where TCDS is used)
* added generation of this FED & event ID to Fake BU generator source
* fix for buffering code when using single input buffer in input source