Ignore .!qB when extracting file extensions

Yes something like that. Although `QString name(filename);` is better because it avoids one copy.

>I opted for remove() because it doesn't matter if stuff before the (real) file extension is removed (which is unlikely given what we are removing) and made the code simpler.

Wouldn't that cause erros if you removed `.!qB` in the middle of the name? It's unlikely to exist but not impossible.