1.0.9

1. Add direct editing and mandatory functions to ER diagram, optimize the display style of ER diagram fields(ER图增加直接编辑必填功能，优化ER图字段展示样式);
2. Add frequency control and caching functions for saving/downloading images(保存/下载图片增加频率控制和缓存功能);
3. The online version saves drawing data to IndexedDB, which makes local data storage more reliable (less prone to loss) and has a larger capacity, and adds reminders related to export and backup(在线版保存绘图数据至IndexedDB，数据本地存储更可靠(不易丢失)、容量更大，并增加了导出备份相关提醒);
4. Optimization of other functions(其他功能优化);