Remove AlfCrypto libraries and perform everything in Python

Remove AlfCrypto libraries and perform everything in Python

The old AlfCrypto DLL, SO and DYLIB files are ancient,
I don't have the systems to recompile them all, they
cause issues on ARM Macs, and I doubt with all the Python
improvements over the last years that they have a significant
performance advantage. And even if that's the case, nobody is
importing hundreds of DRM books at the same time so it shouldn't
hurt if some decryptions might take a bit longer.