Should be resilient to non-existing content items


On an admittedly corrupted database, it can happen that records exist in the vote results table, but no corresponding content item exists.
Because the module builds a dynamic query using dynamically-created predicates and then builds display on the resulting set of ids, the relation with the content items record table is never ensured. The module then crashes on this line:
results.Select(id => _contentManager.BuildDisplay(_contentManager.Get(id), "Summary"))

This code should be made resilient to such data, by either loading items first and eliminating the null ones, or by doing the fix in core, so other modules benefit from it and don't crash under similar circumstances.

Bonus points for doing a multiple id get instead of several gets...