rename ImagePart to Texture
rename ImagePartConfig to TextureConfig
add TextureManager.ts
add JsonLoader
implements JsonLoader
move AssetsManager into assets folder
add ImageManager
Implements ImageManager
move TextureManager into assets
refactor AssetsManager
implements TextureManager
refactor AssetsManager
rename AssetsManager to AssetsLoader
loading texture atlas
move Texture into assets folder

delete texture folder
implements TextureManager
implements TextureManager
refactor Onion.ts
refactor Texture.ts