Beamline timings

Everything runs on different clocks!

Trigger board: clock starts at start of spill, 10 ns ticks.
Digitizer: provides UNIX time (number of seconds since 1st January 1970), along with a second register describing the number of nanoseconds within the second.
Also provides trigger timestamps for each of the groups. These are defined wrt start of spill, so the ones we should use. 8.5 ns clock.
MWPC: a mess of timings:

I believe I have corrected parsed all this in the ReformatMWPCData function (defined in BeamlineUtils). Should have a single timestamp on a 1.18 ns clock.

Added BeamlineTimings analyzer module to look into all this in more detail. Right now I can't make sense of it all. Bill has mentioned that LArIAT had to apply corrections. I'm guessing we'll have to do something similar to this.