v0.2.0

1. Fully supports annotation of multi-frame DICOM files, and has the ability to annotate multiple frames of images at the same time;
2. The underlying dependency is switched from LabelFile to ImageLabel. ImageLabel supports maintaining the annotation state to avoid repeated loading of files when switching frame;
3. Adjust the format of the output annotation file to better adapt to multi-frame annotation situations;
4. Some issues fixed;