* Fixed nullability warnings in `Utility.cs`
* Fixed a number of nullability issues and warnings
* More nullable fixes
* Fixed the overwrite issue
* Fixed additional nullability issues
* Removed additional nullability issues
* More nullability fixes and added some xmldoc
* Added more xmldocs and removed an unused argument
* Removed more warnings
* Added test to verify that compression modules will mask duplicate entries, if present
* Because there are likely many, otherwise valid, dindex zip archives with duplicated blocklists out there, the log message is now verbose.
To make sure we no longer create archives with duplicated entries, the `--unittest-mode` option makes this a warning that is checked in most tests.
* Added guard in `IndexVolumeCreator` to prevent creating zip files with duplicated block lists.
* Added debug check for duplicates
* Fixed the duplicate test
Kenneth Skovhede