Fix question bank validation bug

[dmols]

The Question Bank feature allows the user to decide how many of questions show on the player side. The value used is set manually and it can't go below or over a specific range, but it's currently not listening to user changes such as deleting questions. This invites a very odd case where the question bank does not work as intended when moving to the player. For this reason, the simplest solution is to make the question bank value the minimum number between itself and the total question count, on save, for starters.