Issue 173 helicity decoder

Created by: mholtrop

This code allows semi-correct () decoding for the "old" style data, were 40 helicity decoder banks show up in one event, and the correct type data where this bank is in each event. () Semi-correct because it will only parse one of those 40 helicity decoder entries.

The code was tested on run 19400 file 40, which has helicity decoder data every event, and 19407 which has 40 in one event and no crash or error is observer.

Please double check the parsing of the timestamp information.