message: Expose image resource to public API
diff: /**
  * @namespace PIXI
  */
  +import ImageResource from './textures/resources/ImageResource';
  +
  export * from './const';
  export * from './math';
  @@ -35,6 +37,11 @@ export { default as Spritesheet } from './textures/Spritesheet';
  export { default as FrameBuffer } from './textures/FrameBuffer';
  export { default as CubeTexture } from './textures/CubeTexture';
  export { default as BaseTexture } from './textures/BaseTexture';
  +
  +
  +// image resource
  +export { default as ImageResource } from './textures/resources/ImageResource';
  +
  export { default as ArrayTexture } from './textures/ArrayTexture';
  export { default as Texture } from './textures/Texture';
  export { default as RenderTexture } from './textures/RenderTexture';
  