v1.4.0

Changelog

• Fix a bug with files being accidentally deleted when two remotes sync to the same third remote, under some conditions
• Rework how last sync time is handled, creating a new sync history
• Avoid syncing files in a directory when the directory has been deleted
• Add flashcards to sync targets
• Add an option to replace the default SiYuan sync menu
• Reduce the number of API calls during the directory scanning process
• Refactor the sync code fully

Full Changelog: v1.3.2...v1.4.0