initial commit of new set diff Table function
initial commit of new set diff Table function

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