added a factory (driven by extension point) allowing to create the
MessagingSystem to most adapted to the current platform
addded a shared instance for component who don't whish their own
presentation 
in many case the behavior is almost the same as using the same
baseMessageGroup when creating a new MessagingSystem since the platform
will try to share UI resource (like console) of the MessaingSystem
instances if they have the same baseMessageGroup.