add RipleyKEstimator class
add RipleyKEstimator class

AustereCuriosity/astropy,astropy/astropy,funbaker/astropy,astropy/astropy,saimn/astropy,AustereCuriosity/astropy,AustereCuriosity/astropy,funbaker/astropy,pllim/astropy,kelle/astropy,aleksandr-bakanov/astropy,DougBurke/astropy,funbaker/astropy,StuartLittlefair/astropy,kelle/astropy,aleksandr-bakanov/astropy,dhomeier/astropy,dhomeier/astropy,dhomeier/astropy,larrybradley/astropy,lpsinger/astropy,StuartLittlefair/astropy,AustereCuriosity/astropy,pllim/astropy,stargaser/astropy,stargaser/astropy,mhvk/astropy,mhvk/astropy,DougBurke/astropy,funbaker/astropy,MSeifert04/astropy,StuartLittlefair/astropy,DougBurke/astropy,lpsinger/astropy,dhomeier/astropy,bsipocz/astropy,saimn/astropy,larrybradley/astropy,pllim/astropy,kelle/astropy,StuartLittlefair/astropy,astropy/astropy,larrybradley/astropy,kelle/astropy,StuartLittlefair/astropy,larrybradley/astropy,aleksandr-bakanov/astropy,bsipocz/astropy,lpsinger/astropy,saimn/astropy,mhvk/astropy,larrybradley/astropy,lpsinger/astropy,dhomeier/astropy,saimn/astropy,kelle/astropy,stargaser/astropy,astropy/astropy,mhvk/astropy,AustereCuriosity/astropy,DougBurke/astropy,MSeifert04/astropy,aleksandr-bakanov/astropy,saimn/astropy,pllim/astropy,astropy/astropy,pllim/astropy,bsipocz/astropy,MSeifert04/astropy,stargaser/astropy,lpsinger/astropy,MSeifert04/astropy,bsipocz/astropy,mhvk/astropy