Add check for unit compatibility
Add check for unit compatibility

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