Fixed IP block removal

- Also removed for countries/cities which have been kept and have no blocks in the new database
Added test for deleted duplicate city

- City moved from one region to another, where there already was a city with the same name
- Handled as a city code update
Added test for duplicate regions (new region with the same name as an old one)
Updated city lists in new or deleted regions before considering kept regions

- Added tests
Added tests for cities moving from/to a region with updated code