Subrubric point consistency

[blerner]

When we have an Exactly-One rubric worth N points, and it has a collection of sub-rubrics in it, we should ensure that all the subrubrics are worth N points, and we should disable their point-totals and automatically populate them with the points from the parent rubric.

[blerner]

More generally, we need to ensure that all paths through the rubric tree produce the same point totals as the part rubric expects. (This is especially pernicious if we have Use any of (Use exactly one of (if perfect or hopeless)) or (otherwise), when that outermost one should definitely be a Use exactly one of...)