MINOR: make use of the array syntax for indexes
MINOR: make use of the array syntax for indexes

camfindlay/silverstripe-forum,gordonbanderson/silverstripe-forum,camfindlay/silverstripe-forum,Olliepop/silverstripe-forum,Olliepop/silverstripe-forum,gordonbanderson/silverstripe-forum,mandrew/silverstripe-forum,mandrew/silverstripe-forum