a little cleanup in PowerSpectrumRealizer methods to get kappa
(#304)
get convergence from PowerSpectrum
(#304)
Merge branch '#304' of https://github.com/GalSim-developers/GalSim into #304
some fixes for lensing engine with convergence
(#304)
made lensing example code use PowerSpectrum, not PowerSpectrumRealizer
(#304)