We do this by looking for whether the items are connected to one of the
special Mahara groupings. If they are, we read the display order and use
it - otherwise, the display order isn't used, as we assume the display
order is for some other selection that is irrelevant to Mahara. This
assumption might need to change in future.

Signed-off-by: Nigel McNie <nigel@catalyst.net.nz>