Databases with mutiple file extension (e.g. FRGC).

Hello, In the current CSV-based implementation of database wrappers, we specify the extension of the files to load as an argument of the sample loader.

This poses problem for example in the particular case of bob.bio.face.database.FRGC which has some images stored as .JPG while some others are stored as .jpg. Currently trying to load the latter ones raises an error, as the loader looks only for a .JPG extensions.

I think the most straightforward fix would be for the sample loader to accept a list of valid extensions and try all of them at loading time. What do you think ?

Also, I wonder if this type of situation is very niche (i.e. I will implement a custom sample loader just for FRGC), or if it would make sense to update the default CSVToSampleLoaderBiometrics to generally handle this type of case ?

Another case were it could be useful is to implement some cross-database evaluation protocols (e.g. samples from database A as models and samples from database B as probes), where we could have different extensions as well. I had to do this kind of evaluation in the past when comparing FFHQ against Syn-Multi-PIE.

ping @tiago.pereira