Remove event concatenator.
Remove average flows option.
Disable diff. flows; needs a new implementation.
Convert Particle class to collections.namedtuple.
Use new Particle in urqmd reader.
Add function to generate Particles from files.
Remove unecessary module import.
Use new particle.from_files to generate events.
Flows takes an event instead of a list of phi.
Remove Event class.
Remove string representation of Flows.
Add function to flatten flow vectors.
Flows:  remove minparticles option, store number of particles.
Update Flows docstring.
Update flows executable for new classes.
Update UrQMD parser to read directly from  files.
Update reader to new libs.
Convert particlefilter from class to function; update docstring.
Move input functions to separate module.  Rename event module to flows.
Update scripts for lib changes.