Strong lensing correction

[drphilmarshall]

One possible origin of the excess in galaxy-galaxy lensing power seen at sub-20 arcsecond scales is that we are not predicting galaxy shapes correctly in the "strong lensing" regions where $|g| > 1$. In combineKappas, whenever the magnitude of the total reduced shear rises above unity, we need to replace $g$ with $1 / g^{*}$. (The reference is one of the Seitz and Schneider papers.) Interested to see whether this has any effect on the galaxy-mass correlation function plot!