Eventbuilder: Added evaluation of trb3 trigger type from first data

Eventbuilder: Added evaluation of trb3 trigger type from first data
stream as "eventID" for event header (new
function SubEvt_trigType_trb3).This is read from bit 4..7 of decoding
word of subevent header. If this trb3 trigger type is non zero, it will
define eventID. If not, fallback to trb3 behaviour: eventID is evaluated
from CTS data word 2 with shift/mask procedure of SubEvt_trigType()
function.