Merge branch 'polyobject-scroll-hotfix' into 'next'

Polyobject scroll hotfix

Things fixed:

* Polyobjects should now carry the same thing types as conveyors (notable example; they'll now carry Crawlas when they wouldn't before)
* The drifting issue with players on spinning polyobjects should be fixed. (I swapped in the old bad hack for a new hack that should work like it's supposed to)

See merge request !6