publications from other episodes remain on screen when editing new episodes

[joshlong]

if you switch to an old podcast episode (which have been published), then switch to a new episode with no publications, the old publications from the old episode remain on screen. they need to be reset/nulled-out, whatever.

[joshlong]

this got fixed by removing the segments attribute from the episode entity and moving to a controller handler method with @Batchmapping