QueueManager can add episodes at the beginning or end of the queue
Finish QueueManager object
Improve QueueManager Documentation
Refactor: Add do_with_rebase_retry functio.

Extracted rebase and retry logic to a function.
Ignore the added test, it was previously left commented out.
Add `add_before` and `add_after` methods to QueueManager
WIP drag and drop
Add drag and drop skeleton
Register drop start, end, and drop events
WIP: Adding drag and drop support to queued episodes
Kludgy queue reordering
I think drag and drop works again
Fix some errors I guess?
Inc counter
Merge branch 'reorder-queue'