switch to duck-typing for location and skycoord objects
switch to duck-typing for location and skycoord objects

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