Allow reordering puzzles from round/meta page

[Torgen]

Currently you can only edit the order of puzzles in a meta from the blackboard. If the ordering of the puzzles for solving doesn't depend on the order in which they were unlocked--for example, if it's based on answer length or a tag--it would be more convenient to be able to reorder them from the puzzle page instead of having to go to the top-level blackboard to do it.