core (memory/encryption): start improvments, stop and getSession: - "start" won't do anything if session is already encrypted with requested algorithm, and will raise a ConflictError if it's already encrypted but with an other algorithm - implemented "stop", with an optional namespace to check we are stopping the expected algorithm - "getSession" retrieve the current encryption session of a jid, if any

[D-BUS Service]
Name=org.salutatoi.SAT
Exec=sat