Features
- Can set desktop image scaling mode. (Issue #3)
- Can build four-photo collection. (Issue #2)
- Use semantic versioning.
Bug fixes
- Fix bug: the about window does not always show up. (Issue #8)
- Fix bug: force canceling does not work at the time of RSS parsing. (Issue #6)
- Fix bug: status control error, to start or to cancel. (Issue #11)