Fixes:
- iCloud sync now receives remote changes without relaunching the app (push notification registration and fetch on activation)
- iCloud sync conflict resolution no longer re-uploads stale content, which could revert newer edits made on other devices
- Closing a tab via "Save" no longer destroys the tab when the save panel is cancelled or the write fails
- An unreadable session or clipboard file is backed up instead of being overwritten with an empty one
- Clipboard monitoring no longer leaks pollers on settings changes (previously kept recording history even when turned off)
- Clipboard entries evicted by the history limit are now also deleted from iCloud
- Re-copied image entries no longer lose their image when the original entry is deleted
- Fixed text corruption and cursor misplacement in checkbox, indent and line operations on lines with emoji
- Undo no longer corrupts text after a file is reloaded from disk or updated by iCloud sync
- Fixed a memory leak in syntax highlighting (one full-document copy per keystroke)
- Language auto-detection no longer freezes the app after pasting very large documents
- File save failures now show an alert instead of failing silently
- Links now open with Cmd+click, so link text can be selected and edited normally
- Fixed a race in external file change watching
- Markdown previews in split panes no longer show stale content