There is absolutely no need for having a "Client" class in the FileListDatabase implementation

In the current implementation of the FileListDatabase, there are functions generating and returning Client's. The Client itself just stores the client_id and nothing else. Furthermore, the Client is used nowhere inside the biometric toolchain, only the client_id is used.

I think, the Client class and according functions of the FileListDatabase were introduced for legacy purposes, i.e., to be comparable to other low-level databases. As we have decided to distinguish between low-level and high-level databases (and the FileListDatabase is a high-level database only, I don't think that we need the Client class here.

Any opposition for removing those? They mess up the documentation here: https://www.idiap.ch/software/bob/docs/bob/bob.bio.base/master/implemented.html#bob.bio.base.database.Client by documenting a Client class in the middle of BioFile, BioFileSet and FileListBioDatabase...