Merge tag '2.6.0' into develop

* Adaptation to YouTube API change. (#383, #388, #385, #382)
* Include DASH formats URLs in `streamURLs`. (#354)
* Add new `autoGeneratedCaptionURLs` and `captionURLs` properties to `XCDYouTubeVideo`. (#281)
* Fix `Messaging unqualified id` warnings. (#393)
* Deprecated `smallThumbnailURL`, `mediumThumbnailURL`, `largeThumbnailURL`. Use `thumbnailURL` instead.

XCDYouTubeKit/XCDYouTubeVideo.h

@@ -15,7 +15,7 @@ NS_ASSUME_NONNULL_BEGIN
 /**
  *  The quality of YouTube videos. These values are used as keys in the `<[XCDYouTubeVideo streamURLs]>` property.
  *
- *  The constant numbers are the YouTube [itag](https://en.wikipedia.org/wiki/YouTube#Quality_and_formats) values.
+ *  The constant numbers are the YouTube [itag](https://en.wikipedia.org/wiki/Talk:YouTube/Archive_22#Moved_from_YouTube#Quality_formats) values.
  */
 typedef NS_ENUM(NSUInteger, XCDYouTubeVideoQuality) {
 	/**