yattee://x-callback-url/{verb}?… runs the same action as yattee://{verb}?…
and then opens x-success with the result's values appended, x-error with
errorCode/errorMessage, or x-cancel when a confirmation is declined (x-error
with errorCode=cancelled when no x-cancel is given). Unknown verbs report
unsupportedAction. Callbacks to file:, javascript: and data: URLs are ignored.
Adds yattee://player/state, which reports what is playing (title, videoID,
channel, playing, position, duration, rate) without changing anything.
c579ee63a2