Release v1.0

- [x] Create `rel/0.x` branch for legacy issues
- [ ] Complete `php-exif-exiftool` rewrite
- [ ] Rewrite `php-exif` code (factories basically)
- [ ] Update composer.json: suggest `php-exif-native` and `php-exif-exiftool`
- [ ] Write documentation in `php-exif-native` and `php-exif-exiftool` repositories + refer to it from here
- [ ] Implement issue #22 