problem

the installer just unpack the content of the received file. This does not delete old or not used anymore files. This is possibly dangerous since unwanted / unneeded files remain.

There is already a concept which deletes files listed in a filesToBeDeleted.txt list, but this must be improved in the following way:

All files in the application_root are compared recursively with a blacklist.

1. The blacklist contains all file paths from the current ZIP file.
2. A hardcoded list of whished files / directories, like the data/ directory
3. The list of extract targets from the dependencies list (since this directories are maintained via the dependency manager)
4. The list of license files from the dependencies (all non listed license are not desired)
5. The plug-in directory. Since plugins can be installed manually, nothing should be deleted automatically in the plugin directory. Should ever a plugin be removed (like in the near past the matchresource plugin) it should be listed in the filesToBeDeleted.txt file

All files which are not in that complex blacklist are removed, same is for folders. If a folder is in the blackliste, it is not entered for removing.