core: new EncryptionHandler class which manage encrypted session as a core feature: Plugin handling encryption can now register using host.registerEncryptionPlugin, and an encryption session can now be started using messageEncryptionStart bridge method. This will make encryption handling more easy, as we now know if a session is clear or e2e encrypted, and which plugin handle it.

include MANIFEST.in sat/VERSION
global-include *.py
global-include *.ini
global-include *.po *.mo
global-include CHANGELOG COPYING* INSTALL README*
global-include *.sh
include src/sat.*
include misc
include frontends/src/jp/jp frontends/src/primitivus/primitivus
include src/bridge/bridge_constructor
global-exclude *.un~
prune src/bridge/bridge_constructor/generated