Improve calculation of default spacing when in decimal mode
Improve calculation of default spacing when in decimal mode

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