integrate non-axisymmetric potentials as lists, such that we actually use C
fix bug in docs
print warning messages when C libraries are not installed; fixes 146
start on module to test streamdf; add expected failure decorator
check misalignment, freqEigvalRatio, and that the progenitor and track are close together
tests of the spread around the track in 2D (used by the plotting code)
don't cover pot=None
a few more track and spread cases
fix interp test