Removed legacy components

bob/learn/pytorch/extractor/audio/DummyExtractor.py

bob/learn/pytorch/extractor/image/DeepPixBiS.py

bob/learn/pytorch/extractor/image/FASNet.py

bob/learn/pytorch/extractor/image/LightCNN29.py

bob/learn/pytorch/extractor/image/LightCNN29v2.py

bob/learn/pytorch/extractor/image/LightCNN9.py

bob/learn/pytorch/extractor/image/MCCNN.py

bob/learn/pytorch/extractor/image/MCCNNv2.py

bob/learn/pytorch/extractor/image/MCDeepPixBiS.py

bob/learn/pytorch/preprocessor/audio/DltResNet.py

doc/guide_audio_extractor.rst