Algorithm.read_toscore_object should not exist

Similarly to the bob.bio.base.algorithm.Algorithm.read_probe (see bob.bio.base#79 (closed)) the algorithm in bob.pad.base should not contain a specific function to read the probe files, but should solely rely on the read_feature function of the extractor or the algorithm. See bob.bio.base!78 (merged) for a possible route for a solution.