Apart from app name, which at the moment is the same no matter what language, there are URLs here. They shouldn't reside here but make them (and the app name) at least "translatable=false".
+ Implemented timestamps
* renamed `VideoInfoItem` to `VideoPreviewInfo`
* Moved streaming service-related classes into their own, new package: "services"
+ Added javadoc to some classes and methods (where functionality is known well enough to explain)
- De-duplicated common fields between `VideoInfo` and `VideoPreviewInfo` by moving them into a common superclass: `AbstractVideoInfo`
- Removed 2 methods in `PlayVideoActivity` which only call `super()`, and therefore are unnecessary: `onResume()` and `onPostCreate(Bundle)`
+ Added `VideoInfo(AbstractVideoInfo)` constructor
- to support converting `VideoPreviewInfo`s into `VideoInfo`s, to reuse scraped info (yet to be implemented)
* Made the Extractor class behave as a per-video object;
- most method return values are video-specific, so it makes sense (to me) to have Extractor be stateful.
- The only stateless methods are getVideoUrl(), getVideoId() and loadDecryptionCode(String)
* Implemented a constructor for YoutubeExtractor, which performs all initialisation work, such as fetching `Jsoup.Document`, and `playerArgs:JSONObject`
* added VideoInfo(AbstractVideoInfo) constructor, to support later implementation for reusing info scraped into VideoPreviewInfo, into VideoInfo
* Made the Extractor class behave as a per-video object;
- most method return values are video-specific, so it makes sense (to me) to have Extractor be stateful.
- The only stateless methods are getVideoUrl(), getVideoId() and loadDecryptionCode(String)
* Implemented a constructor for YoutubeExtractor, which performs all initialisation work
* renamed VideoInfoItem to VideoPreviewInfo
* moved streaming service-related classes into their own, new package services
* added javadoc to some classes and methods (where functionality is known well enough to explain)
* De-duplicated common fields between VideoInfo and VideoPreviewInfo by moving them into a common superclass: AbstractVideoInfo
* Removed 2 methods which only call super(), and therefore are unnecessary: PlayVideoActivity.onResume() and PlayVideoActivity.onPostCreate(Bundle)
