Added option to return kappa magnification field along with g1, g2 fields when generating fields.
Fixed the kappa map creation so it produces sensible looking fields.
Per Rachel suggestion, precompute the geometric part of the kappa term.
Corrected a switch between k_x and k_y in calculating kappa
Fixed a bit where I claimed a thing was real and so did not need a conjugation when it is not.
Switched to a simpler form of the equations and hopefully fixed a bug.  Still need to test more, though.
Fixed a sign error in the old shear part of the code.  Or possibly introduced one, but hopefully not.
Addedan example of generating and plotting combined shear and kappa fields.
Merge branch 'master' into #304
Merge branch 'master' into #304
added docstring for NFWHalo test
(#304)
Merge branch 'master' into #304
Merge branch 'master' into #304
Merge branch 'master' into #304
Merged master into #340
Merge branch 'master' into #304
Merge branch 'master' into #304
first stab at a kaiser squires inversion routine, not getting good or consistent results
(#304)
mmmm debugging...
(#304)
a little cleanup in PowerSpectrumRealizer methods to get kappa
(#304)