Position should be updated from arroost to nogan

[TodePond]

done on dummy, just needs doing more generally. eg some helper somewhere like carry or tunnel

[TodePond]

also, double check perf: it feels like we're doing it too much still!? what is causing too many refresh propagations? sure we can use spatial hashing further down the line, but i feel like it should be faster as it currently is now

[TodePond]

found out we dont need to do it initially, just on subsequent changes.

and made it part of tunnel so it can be reused