Added normalized_epsilon as a parameter to convolve_fft
Added normalized_epsilon as a parameter to convolve_fft

This allows the user of convolve_fft to choose the upper limit of deviation between the kernel sum and unity, so that it can for example be adjusted for the specific floating-point precision of the kernel array
mhvk/astropy,bsipocz/astropy,lpsinger/astropy,stargaser/astropy,lpsinger/astropy,aleksandr-bakanov/astropy,DougBurke/astropy,funbaker/astropy,pllim/astropy,kelle/astropy,aleksandr-bakanov/astropy,larrybradley/astropy,MSeifert04/astropy,pllim/astropy,AustereCuriosity/astropy,larrybradley/astropy,MSeifert04/astropy,saimn/astropy,mhvk/astropy,dhomeier/astropy,dhomeier/astropy,larrybradley/astropy,AustereCuriosity/astropy,astropy/astropy,MSeifert04/astropy,MSeifert04/astropy,stargaser/astropy,AustereCuriosity/astropy,StuartLittlefair/astropy,dhomeier/astropy,AustereCuriosity/astropy,funbaker/astropy,astropy/astropy,aleksandr-bakanov/astropy,dhomeier/astropy,bsipocz/astropy,astropy/astropy,saimn/astropy,kelle/astropy,kelle/astropy,astropy/astropy,saimn/astropy,StuartLittlefair/astropy,saimn/astropy,astropy/astropy,DougBurke/astropy,lpsinger/astropy,lpsinger/astropy,aleksandr-bakanov/astropy,mhvk/astropy,DougBurke/astropy,DougBurke/astropy,kelle/astropy,StuartLittlefair/astropy,funbaker/astropy,StuartLittlefair/astropy,larrybradley/astropy,larrybradley/astropy,StuartLittlefair/astropy,funbaker/astropy,stargaser/astropy,bsipocz/astropy,mhvk/astropy,mhvk/astropy,kelle/astropy,bsipocz/astropy,stargaser/astropy,lpsinger/astropy,dhomeier/astropy,pllim/astropy,saimn/astropy,AustereCuriosity/astropy,pllim/astropy,pllim/astropy