Move _setitem_validated to __setitem__ w/ validated kwarg
Move _setitem_validated to __setitem__ w/ validated kwarg

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