Merge File Selection

[t71rs]

Deletion of Files when using Merge

In my opinion, the process of selecting files for the merge operation is a bit clunky. An example to understand what I mean:

1. Select one or more files via the "Select File" button provided.
2. Repeat this process --> Files that have been added before are now deleted.

Proposed Changes:

1. Do not delete the files that have been added before: For instance, if you forgot one file, you shouldn't have to select all of them again along with the extra file to merge them.

2. Handling duplicates: Duplicate files can already be added using drag and drop. Implementing the changes would mean that this can also be done with the file selector. In my opinion, it should be possible to add a file more than once, but maybe the UI should give a little warning in case it was a mistake.

If you approve this, I would like to start working on implementing these changes.