Add THcTimeSyncEvtHandler

  This event type handler can be used to gather statistics on the slippage
  of trigger times in FADC250 headers.
  It looks at the relative trigger times between the ADCs and the TI modules
  and counts the number of times the relative times shift.

  The ADC trigger times will have a small offset relative to the TI trigger
  times.  The method AddExpectedOffset(roc, offset) allows the setting
  of this offset on a crate by crate basis.  If expected offsets are not
  set, the first event is used to determine the offsets.