* AssetManager's textureLoader returns Texture.
* AssetManager#loadTexture success gives a Texture.
* TextureAtlas no longer has a textureLoader, it creates all the pages without a texture set.
* TextureAtlasRegion no longer has a texture, use region.page.texture instead.
* AssetManager#loadTextureAtlas no longer parses the atlas text twice. It creates the atlas, then loads and sets all the textures.
* Rendering, added support for separate color/alpha src blend funcs.
* LoadingScreen, set camera zoom to fade out and black flash, use PMA to fix ringing artifacts when scaled, fade in to help hide dropped frames as page loads, use separate color/alpha src blend funcs to properly blend quad when loading screen fades out, oxipng PNGs.
* Moved some private constants out of their class to avoid class name prefix.
* Player, clean up full pass OCD town, showError throws when possible so stacktrace isn't lost, added showLoading to config, don't create UI when !showControls, removed findWithId (id is unique for entire document), use built-in for findWithClass/contains, var->let, don't clear screen twice during loading, other minor stuff.
* Removed # parsing from SpinePlayer, replaced with config.jsonField.
* Refactored AssetMananger to split downloading from asset creation.
* Allow Downloader to be specified in SpinePlayer config so multiple players don't download the same assets.
* Added AssetManager#loadJson so the text is only parsed once.
* TextureAtlas is still parsed multiple times. :(
* AssetMananger clean up, catch more errors, log error, don't keep rendering after an error.
