Podcasts shipped switched off in every release and are now removed from the server,
web client and shared types. Migration 0132 drops the podcast tables and the media-type,
library-type and folder-role columns. Released iOS and Android builds read the removed
response fields as optional, so the API change stays compatible.
Promote Viewer grants to Editor on book libraries for non-superusers who hold Edit metadata but
can edit nowhere, which is how every such account was left after the upgrade. Accounts with any
Editor or Owner role are left alone. The Users drawer now says where Edit metadata takes effect,
read from a new GET /users/:id/library-access route.
Closes#1902
neon