Reverse playlist is back

This version includes a feature that was very popular in the past, and requested again many times; the ability to reverse playlists. This feature shows a button on the video page playlists that allows the playlist order to be reversed. This also affects the previous and next video buttons in the player, as well as the video that is set to play automatically next.

Another feature implemented in this version is the ability to control channel trailer autoplay. This setting is separate from the video page autoplay and should not interfere with it.

A few fixes are also included; channel count not working in a different YT UI, channel blacklist not covering trending, gaming, and podcasts feeds, and the YT mini player controls not working when the autoplay is disabled.

For a full list of changes check the milestone: https://github.com/ParticleCore/Iridium/milestone/23?closed=1