Minor modifications to Yvar's A* fixes:

-Removed the priorityqueue datum. It is now a list()
-priorityqueue/proc/insert is now a helper /proc/sorted_insert() as it may be helpful in maintaining pre-sorted lists or insertion sorts.
-Replaced priorityqueue/proc/extract_last() calls with calls to pop(), which already existed.
-Removed last few references to "bestF" (from old awful A) in lighting and MC
-Replaced a section were it'd append to the end of the returned path list and then reverse the list. Now it inserts at the start of the list.

Please check I haven't broken anything :blush: