Added wake lock permision to android manifest
Added a loading screen for loading textures in the background.
- Made the loading screen be the one to start.
- Moved the resourceManager.startLoad to the loading screen.
- Made GameController override resume and handle reloading of textures when app is resumed from pause (this only really applies to android).
- Added a blocking parameter to ResourceManager.load and renamed the method to startLoad.
- Added a loadAsync method to ResourceManager that forwards calls to the internal asset manager's update.
- Made ResourceManager re-create the static AssetManager every time it is constructed, as the AssetManager is disposed when app is destroyed.