Add polyco class (in predictor.py)
Add documentation to polyco
Test case, layout; need to add ephemeris calculation
par2dist and polyco predictor updates
Corrections to predictor/polyco -- now can do arbitrary zero points and time scales
Corrections to Polyco, mostly to ensure it still works with Time scalars
Split off ELL1 from general pulsar ephemeris; corrections to par2dict
barycentre: Treat Time objects in full precision in calls to jplephem
Update of predictor documentation
Allow comment lines in reading pulsar ephemerides