Reduce activation once broadcasted

[pulinagrawal]

According to our conceptual model, if a content is broadcasted it's activation in the Current Situational Model should be brought down to 0. Rationale is that once a content is broadcasted its immediate relevance/salience to the agent is reduced. Almost any other content is currently more important than this content. The content whose activation is forced to be 0 may gain activation again if it is still relevant.