New features:
1. Support iCloud Synchronization
2. Cover Image Editor: rotate text and image
3. Support Fixed Layout, Landscape, Portrait & Square
4. Fixed Layout & Cover Editor: Double click to edit element
5. Audio Recording
6. Read Aloud (for fixed layout only)
7. Background (for fixed layout only)
8. Soundtrack (for fixed layout only)
9. Auto page title
10. Search book by keywords
11. Filter book by layout type & storage option
12. Export book as PDF
13. Redundant images are not kept
14. Bug fix
