core (memory/crypto): replaced `PyCrypto` by `cryptography`: `PyCrypto` is unmaintained for years but was used in SàT for password hashing. This patch fixes that by replacing `PyCrypto` by the reference `cryptography` module which is well maintained. The behaviour stays the same (except that previously async `hash`, `encrypt` and `decrypt` methods are now synchronous, as they are quick and using a deferToThread may actually be more resource intensive than using blocking methods). It is planed to improve `memory.crypto` by using more up-to-date cryptography/hashing algorithms in the future. PyCrypto is no more a dependency of SàT

syntax: glob
*.pyc
*.pyv
*.swp
*.swo
tags
twistd.log
twistd.pid
bridge_constructor/generated
_trial_temp/
sat.egg-info
*.un~
dist
MANIFEST
build
ctags_links/
Session.vim