change my ridiculous calling of assert to the proper way
some basic tests of actionAngleIsochroneApprox
fix error message; don't cover a bunch of errors
tests of different actionAngleIsochroneApprox setups and of plotting
test estimateBIsochrone
also test angles of actionAngleIsochroneApprox vs. actionAngleIsochrone
fix plotting bug in araphi (found through nose test) and don't cover another error message
few more plotting tests, don't cover a few lines