Feat/image optimize

[andycall]

Fixed #865

1. 支持通过用户设定的图片尺寸，在加载阶段自动裁剪出合适尺寸的图片。
2. 优化图片加载逻辑，当图片被卸载，但是没有销毁的情况下，保留 imageStream。只有 dispose 才会完整销毁图片所持有的资源。
3. 支持复用 imageCache，相同的图片不会被重复加载两次

[tylorvan]

lazy 加载图片报错

======== Exception caught by image resource service ================================================
The following assertion was thrown resolving an image codec:
'package:flutter/src/painting/binding.dart': Failed assertion: line 103 pos 12: 'cacheHeight == null || cacheHeight > 0': is not true.

Either the assertion indicates an error in the framework itself, or we should provide substantially more information in this error message to help you determine and fix the underlying cause.
In either case, please report this assertion by filing a bug on GitHub:
https://github.com/flutter/flutter/issues/new?template=2_bug.md

When the exception was thrown, this was the stack:
#2 PaintingBinding.instantiateImageCodec (package:flutter/src/painting/binding.dart:103:12)
#3 ResizeImage.load.decodeResize (package:flutter/src/painting/image_provider.dart:769:20)
#4 CachedNetworkImage._loadImage (package:kraken/src/painting/cached_network_image.dart:66:20)

(elided 2 frames from class _AssertionError)
Image provider: CachedNetworkImage()
Image key: CachedNetworkImage()

[wssgcg1213]

需要恢复 naturalWidth/Height 的实现

[andycall]

需要恢复 naturalWidth/Height 的实现

done

[yuanyan]

CI 没有通过

[wssgcg1213]

上面这个 import 有点问题, 不知道啥时候引入的

[wssgcg1213]

做成没有 setter 会好一点, 这样貌似可以外部修改

[wssgcg1213]

这里不用换行的

[wssgcg1213]

No logical problems.