* The PIXI.BaseTexture.imageUrl property has been removed, as it was never actually populated.
* The PIXI.BaseTexture._UID property has been removed, as it was never actually used internally.
* All references to PIXI.BaseTextureCache have been removed (primarily from BaseTexture.destroy and Texture.destroy), as the BaseTextureCache was never used internally by Phaser, or by our custom version of Pixi.
* PIXI.TextureCache has been removed. It was only ever used by the __default and __missing images that Phaser generates on start-up. It wasn't used internally by Phaser anywhere else, and the only references Pixi has to it have all been removed. If you need it in your own game, please refactor it to avoid it, or re-create the object on the PIXI global object.
* Canvases created by `BaseTexture.fromCanvas` no longer have the `_pixiId` property attached to them, as this was never used internally by Phaser or Pixi.
* PIXI.BaseTexture.updateSourceImage is now deprecated. Please use `Sprite.loadTexture` instead.
* The property PIXI.BaseTextureCacheIdGenerator has been removed, as it is no longer used internally by Phaser or Pixi.
* PIXI.Texture.addTextureToCache has been removed. The PIXI Texture Cache was never actually used by Phaser, and was leading to complications internally.
* PIXI.Texture.removeTextureFromCache has been removed. The PIXI Texture Cache was never actually used by Phaser, and was leading to complications internally.
* PIXI.Texture.fromFrame and PIXI.Sprite.fromFrame have been removed. They relied on the PIXI Texture Cache, which was never actually used by Phaser, and was never used internally by Pixi either.
* The property PIXI.TextureCacheIdGenerator has been removed, as it was not used internally.
* The property PIXI.FrameCache has been removed, as it was not used internally.
