* Global code & UI redesign.
+ Options for error handling (fixes #2)
+ Ability to add missing EXIF fields (fixes #4)
+ Hint label over empty listview (closes #3)
! "Process" button is disabled only if no files in the listview (fixes #1)
- Simplify handling of RO cases: remove RO flag on load and never set it back
+ Much more flexible logic in processing