Fixed#70: SheerkaFilterManager : Pipe functions
Fixed#71: SheerkaFilterManager : filter_objects
Fixed#75: SheerkaMemory: Enhance memory() to use the filtering capabilities
Fixed#76: SheerkaEvaluateConcept: Concepts that modify the state of the system must not be evaluated during question
Fixed#49 : ExpressionParser: Implement ExpressionParser
Fixed#50 : Implement ReteConditionExprVisitor
Fixed#51 : Implement PythonConditionExprVisitor
Fixed#52 : SheerkaConceptManager: I can get and set concept property