Villagers with XP in a profession do not get prioritized when a new workstation of their craft is placed

Observed Behaviour:

Villagers with XP in a profession (no longer able to change profession) do not get prioritized when a new workstation of their craft is placed.

What should have happened:

Villagers with highest XP in profession should be assigned first to a workstation to prevent cycling through jobless villagers if they are present

Possible fix:

maybe fix with one worker pool per profession per village, assign villager without workplace and highest XP in profession first (possible concurrency problem with multiple villagers assigning them to same workstation fix, see MC-150806)

e.g.: 3 fishers, one with 100XP, the others with 50, 5 jobless

• Workplace of the fisher with 100XP gets destroyed, add him to the village "fisher job" worker  queque.

• Workplace of the fisher with 50 XP gets destroyed, add him to the village "fisher job" worker queque below the 100XP fisher.

• New barrel gets placed, get and remove head element of the "fisher job" queque and assign him to the workplace

• if "fisher job" queque is empty, default to "jobless" queque, if that fails aswell, leave jobsite vacant