remove lots of duplicated imports
remove lots of duplicated imports

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