Making it easier to give jobs to villagers

Make it so that only one villager can be assigned to one jobsite block. For example, one lectern can only make one villager a librarian instead of having the possibility of multiple villagers being a librarian from just one lectern. Also make it so that when you place down a jobsite block, the nearest villager will be assigned to that job instead of having a random villager far away being assigned to that job.