Add contained unit attribute for "points are part of parent"

[ibboard]

Some contained units (e.g. Champions) are sub-units so that you have more control to edit them, but count their points as part of the parent unit (e.g. for victory conditions - Champion points aren't awarded until you wipe out the whole unit).

Others are sub-units because they're separate entities, related through some kind of "command" hierarchy and their points are separate from the parent unit (e.g. a transport is for a unit, and hence a sub-unit, but destroying just the transport gets the points for the transport separate from the unit).

We need an attribute in the data files that represents "points are part of parent", and we need to default to saying that they are not (since that doesn't hide any information, even if it does force users to do a bit of maths).