add actionAngleIsochrone to the top-level
start work on action-angle variables using the isochrone approximation; reading of input
don't allow RZorbits
fix parsing of Orbit instances in actionAngle framework
calculate actions using the isochrone approximation
fix parsing of input to actionAngleIsochroneApprox.__call__
introduce function to parse the arguments for actionAngleIsochrone calls
fix parsing; edit default number of times for sufficient resolution
fix lz sumFunc
add skeleton for estimatebIsochrone