Address EVIO event misordering in helicity sequence detection
Created by: baltzell
- Add a "stream" initializer for HelicitySequence and various convenience methods
- Use it in the decoder when detecting helicity state changes and creating HEL::flip banks
- Plus some new static methods for validating the new helicity decoder board
- In preparation for (re)detecting helicity state changes during postprocessing
- Finish support for direct event access in HipoDataSource
- Extend it to a new HipoDataSourceSorted for ordering by CODA event number
closes #166 (closed)