core (memore/encryption): new methods and checks: Following methods are now available though bridge: - messageEncryptionStop - messageEncryptionGet: retrieve encryption data for a message session - encryptionPluginsGet: retrieve all registered encryption plugin Following methods are available for internal use: - getPlugins: retrieve registerd plugins - getNSFromName: retrieve namespace from plugin name - getBridgeData: serialise session data (to be used with bridge) - markAsEncrypted: mark message data as encrypted (to be set by encryption plugin in MessageReceived trigger) Behaviours improvments: - start and stop send messageEncryptionStarted and messageEncryptionStopped signals, and a message feedback - new "replace" arguments in start allows to replace a plugin if one is already running (instead of raising a ConflictError) - plugins declare themselves as "directed" (i.e. working with only one device at a time) or not. This is checked while dealing with jids, an exception is raised when a full jid is received for a non directed encryption. - use of new data_format (de)serialise