Fix vstack for masking + tweaks for hstack and join
Fix vstack for masking + tweaks for hstack and join

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